Sinopec Group topped the list of the top 500 companies in the Chinese mainland by revenue for the second straight year, according to the 2012 rankings released Saturday in Changchun, Jilin province by the China Enterprise Confederation (CEC) and the China Enterprise Directors Association.

Sinopec's revenues reached 2.55 trillion yuan (US$402 billion) in 2011, earning it the top position on the list. Sinopec is followed by the China National Petroleum Corp and State Grid Corp., whose revenues hit 2.38 trillion yuan and 1.68 trillion yuan last year respectively.

Industrial and Commercial Bank of China, China Construction Bank, China Mobile, Agricultural Bank of China, Bank of China, China State Construction Engineering, and China National Offshore Oil Corporation, all state-owned enterprises, rounded out the top 10.

In aggregate, China's top 500 companies earned 44.9 trillion yuan (US$7.08 trillion) in operating revenues last year, a 23.63 percent year-on-year increase. However, the profitability of these big firms has decreased, with average margins at 4.7 percent, down 1.07 percent from 2010. The average return on assets was 1.6 percent, a 0.32 percent decline.

2011 profits of the top 500 companies remained stable at 2.1 trillion yuan, but the zero growth was in stark contrast to 2009-2010, when 2010 profits rose 38.67 percent year-on-year from 2009.

The 500 listed enterprises paid 3.3 trillion yuan in taxes in 2011, accounting for 37.2 percent of the country's total tax revenues.

The threshold to make the list has now reached US$2.5 billion, a 18.65 percent increase from 2010.

Two other lists, China's Top 500 Manufacturers and Top 500 Service Companies, were also released.

A total of 1,083 enterprises were been ranked on these three lists. Of them, 272 companies from the Top 500 Manufacturers and 145 from Top 500 Service Companies are included in the country's 500 largest firms.

79 Chinese companies made the 2012 global top 500 list as compiled by Fortune magazine, 10 more than last year. Of these companies, 70 are from the Chinese mainland.

China overtook Japan as the second largest contributor to the Forbes 500 list, with US firms still occupying the most spots.

In 2012, 261 firms from the China top 500 reported overseas revenues, realizing an average overseas income of 19.1 billion yuan, an increase of 39.3 percent over the previous year. Average overseas assets reached 29 billion yuan, a year-on-year increase of 28.2 percent. In addition, the average number of overseas employees for these firms was 3108, nearly 30 percent more than last year.