Field experiments and chemical composition analysis of particle in flue gas from several coal-fired power plants in Guanzhong area of Shaanxi province was carried out with dilution and collection system of PM_2.5 in stationary sources designed by the team. The results show that the proportions of PM_2.5 and PM₁₀ in the particles of 4 coal-fired power plants are quite different. The proportion of PM_2.5 ranges from 6.92% to 54.34%, and the proportion of PM₁₀ ranges from 36.36% to 73.02%. Maximum values (2.0×10⁴ to 4.0×10⁵/cm³) of number concentration levels from 4 coal-fired power plants are quite different, and the difference is about 1 order of magnitude. The mass concentration proportion of small particles to PM_2.5 from coal-fired power plants is mostly low, but the small particles' contribution to PM_2.5 number concentration is great (minimum value > 95%), and the situation of the large particles is quite the opposite. The PM₁/PM_2.5 value of the pulverized coal boiler is large, the ratio range is between 35.29% and 51.35%, and the PM₁/PM_2.5 value of the circulating fluidized bed boiler is small, the ratio range is between 16.62% and 21.47%. SO₄^2- is the most abundant ion component in PM_2.5 of coal-fired power plants, and the proportion of SO₄^2- to total ion concentration ranges from 50.02% to 65.52%, Na⁺ and Ca²⁺ ranking second or third. The main inorganic elements detected in the coal-fired power plants are Si, Al, Ca, Na, Fe, Na and other crustal elements. The emission factors' range of PM_2.5, PM₁₀ and particles in the coal-fired power plants are 0.001 to 0.028 kg/t, 0.002 to 0.086 kg/t and 0.003 to 0.236 kg/t, respectively. The more complex and advanced the combination of dust removal facilities is, the smaller the emission factor is likely to be.