"We must be aware that this year would be the worst in recent times for our economic development," Wen said in an article published in the Qiushi journal.
Curbing inflation is still a challenge, even though it fell from a 12-year high of 8.7 percent in February to 4.6 percent in September, he wrote.
In his article, Wen said that the global downturn will continue to pressure the Chinese economy, which already faces a number of problems.
Given the situation across the world, "it is very difficult to maintain high growth and a low inflation rate in the long run," the premier wrote.
"The (global economic) situation is worsening," and the negative impact of the volatile international market on the Chinese economy would become more obvious as the days go by.
The main task of the macro-economic policy is "to successfully maintain a balance between stable and relatively fast economic development and curbing inflation," Wen said.
China's economy expanded by 11.9 percent in 2007, but the growth rate slowed to 9 percent in the third quarter of this year, prompting many experts to suggest that the government take prompt steps to bolster economic growth.
One of the ready choices policymakers have is to relax the monetary policy. But along with many economists, they are worried that too loose a monetary policy could make inflation shoot higher in the future.
Though maintaining economic growth is important, "we should fully understand the harms (serious) inflation can cause to economic growth, people's livelihood and social stability," Wen wrote.
Ma Jiantang, head of the National Bureau of Statistics, however, allayed fears over Chin's economic growth. The fundamentals of the Chinese economy remain sound, and it will maintain a stable growth despite feeling the pinch of the global economic slowdown, he said on Sunday.
Ma told China Central Television that the country has enough means to stimulate investment and domestic demand in order to ensure a stable economic growth.
Though China has maintained a high growth rate for three decades and people's living standards have improved substantially, investment and consumption levels in per capita terms remain low compared with some other countries, Ma said. "The potential is huge."
China's 1.9-trillion U.S. dollars foreign exchange reserve is not only the largest in the world, but also makes it easier for the country to make international payments.
With the country's GDP growth slowing, many analysts are worried that the economy could weaken in the coming months.
As a sign of this weakening, they have warned that growth in fiscal revenue in the fourth quarter of this year will continue to drop after falling from more than 33 percent in the first half to 10.5 percent in the third quarter.
Shanghai feels the pinch
Shanghai Mayor Han Zheng said the global financial crisis has begun hurting China's financial hub.
"We are feeling deeply the impact of the changing global economic environment," Han said at a forum on Sunday.
But the government will take steps to spur investment and consumption, he said.
"A steady and orderly economic growth is our primary task," Han said.
Shanghai's GDP grew 10.1 percent in the first nine months, exceeding the target of 10 percent set for the whole of 2008.