His six-day visit starting on Tuesday, comes a day after US Secretary of State Condoleezza Rice urged China to put more pressure on North Korea to return to stalled six-party talks over the government's nuclear ambitions.
She told her Beijing hosts that Washington was considering "other options" if Pyongyang refused to negotiate.
"If they continue going down this road, not only would the United States, but with Japan, with South Korea, with China and with Russia, not to mention with the rest of world, they're going to have a problem," Rice said.
"Then of course we will have to look at other options ... everybody is aware there are other options in the international system," she said, but reiterated the US had no intention of attacking the Stalinist state.
Increased nuclear arsenal
North Korea responded by saying it had increased its nuclear arsenal in preparation for a pre-emptive invasion by the US, the South Korean Yonhap news agency quoted the North Korean Central Broadcasting Station as saying late on Monday.
"We have taken a serious measure by increasing nuclear arms in preparation for any invasions by enemies," the report said.
"We have taken a serious measure by increasing nuclear arms in preparation for any invasions by enemies"
North Korean Central Broadcasting Station
It said joint US-South Korean military manoeuvres that started at the weekend were "a preparatory war against us".
China has repeatedly urged all parties in the talks to have patience and display flexibility and sincerity in efforts to entice Pyongyang back to the table.
Rice said the US was ready to provide badly needed energy supplies to North Korea if it would agree to verifiably moth-ball its nuclear programmes.
Beijing was actively working to bring Pyongyang back to the talks and remained committed to the goal of a nuclear-free Korean peninsula, Chinese President Hu Jintao told Rice.
Pak will meet Hu on Wednesday afternoon.
He will be formally welcomed at the Great Hall of the People and will hold talks with Premier Wen Jiabao on Tuesday evening.
Chinese Premier Wen Jiabao will
greet Pak at the Great Hall
China has also prepared an elaborate schedule for Pak centred on the achievements of China's 25-year-old experiment with market economic reforms and its integration with the global trading system.
"He has expressed an interest in visiting some of our economic projects and we are more than happy to show him," a Chinese Foreign Ministry official said.
"We think that if they can see the success that China has had in economic reform, then maybe that will help them with their reforms," he added.
Pak's visit follows a secretive trip to China last April by both him and North Korean leader Kim Jong-il, who toured the eastern seaport of Tianjin and visited a formerly impoverished village that quickly enriched itself following China's adoption of economic reforms.
"[Pak] has expressed an interest in visiting some of our economic projects and we are more than happy to show him"
Chinese Foreign Ministry official
Kim also visited China in January 2001, when he toured Shanghai's stock exchange as his government announced its readiness to adopt Chinese style economic reforms.
Despite such efforts, North Korea's economy is still plagued by bad planning, energy shortages and a series of natural disasters that have left the nation struggling as the biggest recipient of UN channelled food aid.