China currently carries out more court-ordered executions than all other nations combined, accounting for 80% of the world's total.
However, Amnesty has cited a senior member of China's national legislature as saying about 10,000 people are executed each year.
Mark Allison, analyst at Amnesty International, told al Jazeera: "It is difficult to know the true figures. Our figures are just the tip of the iceberg."
The document issued by Beijing said: "Our country still cannot abolish the death penalty but should gradually reduce its application.
"But where there is a possibility someone should not be executed, then without exception the person should not be killed."
Along with crimes such as murder, rape, and drug smuggling, the death sentence has also been imposed in nonviolent cases such as tax evasion and corruption.
China has sought to tighten its rules on the application of the death penalty following a series of high-profile cases involving wrongful convictions and torture.
Rules enacted last year restored a requirement that all executions first be approved by the supreme people's court, something that had been waived amid the ongoing "strike hard" anti-crime campaign.
Allison said: "The most positive move in recent months has been the reintroduction of supreme court review, which had been on the cards for many years.
"Observers hope that it will lead to one third reduction in death sentences."
He said: "We will never know how many people are taken out of these death sentences if China keeps statistics on executions secret.
"So we're also calling on China to become transparent in the application of the death penalty and make those statistics public."
Torture or threats
In a famous case in 2005, a woman believed murdered in the 1980s in the central province of Hunan reappeared, 16 years after the man convicted of killing her was executed.
At the time of the execution, the court said the defendant had confessed.
Chinese police often are accused of torturing suspects into making confessions, and the document said it was wrong to use statements obtained through torture or threats "as the basis for a case".
The statement said officials were obligated to "ensure crime suspects and defendants can fully exercise their rights to defence and other procedural rights".
The document said police must be more thorough and obey the laws in identifying and collecting evidence.
It also required officials to ensure that condemned persons were not paraded through the streets or presented before crowds at anti-crime rallies - practices that used to be common but are now usually only found in rural areas.