In order to understand the formations and the concentrations of the secondary sulfate and nitrate of PM10 in Beijing. From May 2008 to April 2009, MOUDI has been used to collect the PM10 samples in Beijing atmospheric environment and the ion chromatography has been used to analyze the inorganic water-soluble components of the PM10 samples. The results showed that the mass size distributions of soluble sulfate and nitrate of PM10 in Beijing were single-mode distribution and the peak rang was from 0.32 microm to 0.56 microm, and the primary formation ways was the chemical reaction in the gas phase. The results of partial correlation analysis indicated that the primary formations of sulfate and nitrate of PM10 in Beijing was (NH4)2SO4, NH4NO3, NaNO3, KNO3 and Ca(NO3)2. The mass concentration of secondary (NH4)2SO4 and NH4NO3 were (17.0 +/- 8.2) microg/m3 and (8.8 +/- 3.3) microg/m3 respectively, which accounted for (14.7 +/- 3.6)% and (7.6 +/- 2.2)% of PM10 respectively. The sum of them accounted for (22.3 +/- 4.3)% of PM10.