The constitution is part of a peace deal between the government and leaders in the south of the country. At the end of the six years, the south will vote on whether to remain part of the country or become independent.
The peace accord, signed in January, ended what was Africa's longest-running conflict.
Amid shouts of "Allahu akbar," (God is great) and "Hallelujah, hallelujah!" the lawmakers stood with their hands in the air to pass the constitution, the first Sudanese charter to lay out freedoms of religion and expression as human rights.
"The state of Sudan is an embracing homeland, wherein races and cultures coalesce and religions conciliate," reads the first sentence of the document.
The six months leading up to this week were devoted mainly to enforcing a ceasefire and drafting a transitional constitution by representatives of the Khartoum government and former southern rebels from John Garang's Sudan People's Liberation Movement (SPLM) and other opposition groups.
During the first four years of the interim period and until general elections are held, the ruling National Congress Party will have 52% of executive posts and legislative seats and the SPLM 28%.
Fourteen out of the remaining 20% will go to northern opposition parties, with the remaining six per cent to be split among other southern groups.
Attention to detail
Aljazeera's correspondent in Khartoum, Mohamed Fal, said the parliamentary session began at 10.30am and each article of the constitution was reviewed and voted on one by one. The constitution drafting committee looked at amendments recommended by committee members.
Turnout was 296 out of 330 members of parliament, reflecting the largest turnout since establishing the parliament, Fal said.
Shaikh Hassan al-Turabi was
Most MPs have expressed support for the constitution, with the exception of a few who do not oppose the constitution but believe it should have been put to a referendum. The chairman said amendments are still under consideration.
The constitution is expected to be unanimously approved at the end of the session.
Some parties, however, remain opposed to the constitution, the most prominent being the Umma party, led by Sadiq al-Mahdi, and the Popular Congress party led by Dr Hassan al-Turabi who has released from jail just a few days ago.
With respect to the National Opposition Alliance, an agreement was forged with the ruling party in Cairo last month, but no quota for power-sharing has been allocated for this opposition alliance, Fal said.
Garang will take up his new vice-presidential post at a ceremony on Saturday and Umar al-Bashir will stay on as president. They will then form a national unity government.
Sharia, or Islamic law, will only apply to the Arab-Muslim north as southern Sudan is mainly Christian and animist.
The south will have its own separate constitution reflecting its customs and traditions, although the national interim charter will take precedence.
Several southern militia commanders still have to sign on to the Comprehensive Peace Agreement and will not be represented in the interim institutions.
Most of Sudan's oilfields are in
the south of the country
Such strategic fields as national defence, foreign policy, national economic policy and planning will be the responsibility of the joint government.
In addition, a joint oil commission will be the sole authority to award concessions. Most oilfields lie in the south.
The SPLM's armed branch - the Sudan People's Liberation Army (SPLA) - has between six and 15 months left to withdraw its forces from northern Sudan.
The national army has another 24 months to redeploy from southern Sudan.
Both should have started withdrawing immediately after the January peace deal but have fallen behind schedule.
In line with the principle of wealth sharing, the economic and social development of southern Sudan will be the shared responsibility of the national government and the government of southern Sudan.
Southern Sudan will have a conventional banking system, while that in the north will continue to operate on Islamic principles.
Around two million people died
during the civil war
Southern Sudan needs billions of dollars to rebuild its infrastructure after 21 years of war and has to grapple with the return of tens of thousands of refugees, poor harvests and the looming threat of famine.
An estimated two million people died during the north-south conflict, mostly of hunger and disease, and another four million were displaced.
Donors pledged nearly $600 million last April in support of Sudan's peace, but not all has been committed let alone disbursed.