Abstract: In order to study the variation characteristics of PM_2.5 and PM₁₀ concentrations in the urban area of Hangzhou, we monitored PM_2.5, PM₁₀ concentration and meteorological characteristics for 1 a in monitoring area of Caihe. The result showed that concentration of PM_2.5 in winter and spring was higher than in summer and autumn, the max concentration in winter was 104.35 ± 99.86 mg/m³. The PM₁₀ in winter was much higher than in other seasons, the concentration was 274.39 ± 160.92 μg/m³. The concentration in spring and autumn were twice that of summer. This shows that a PM₁₀ particle has more diverse sources than PM_2.5, more complex composition. They have different relative concentration and the change law of PM_2.5 and PM₁₀ in different season. The concentration diurnal variation of PM have similar change process in different seasons, and the peak value decreased gradually in the observation period, the value varied with season. PM_2.5/PM₁₀ values range from 0.26 to 0.58, the mean value in winter and spring were 0.51 and 0.50, and were 0.34 and 0.32 in summer and autumn, respectively. It showed that PM_2.5 in a high proportion of pollutants in summer and autumn. There was a significant negative correlation between PM_2.5, PM₁₀ concentration and temperature, and the correlation coefficients were 0.619, 0.640, respectively. The concentration of PM_2.5 and PM₁₀ has a significant positive correlation with atmospheric pressure, and the correlation coefficient was 0.559 and 0.583, respectively.