The shelter forest belts adjacent to the north fifth ring road in the northern part of the Beijing Olympic forest park were chosen as the research object, five monitoring points were set up inside and outside the shelterbelts to locate and monitor for three months. The temporal and spatial variation of PM_2.5 mass concentration was analyzed inside and outside the shelterbelts at the same time, and the correlations were established among PM_2.5 mass concentration and wind speed, temperature, relative humidity and other weather conditions, for a purpose of analyzing the effect of various meteorological factors on PM2.5 mass concentration. The results showed that: 1) as for the temporal variation, PM_2.5 mass concentration inside the shelterbelts presented a single-peak or bimodal distribution (peaks at 08:00 and 12:00, respectively, and the mass concentration was lower at other time), and increased significantly only about 18:00 p. m. . There was roughly a similar pattern of diurnal variation of PM_2.5 mass concentration inside and outside the shelterbelts. 2) The PM_2.5 mass concentration inside the shelterbelts was higher than outside, and that at 40 m away from north five ring road inside the shettbelts was relatively higher than other locations. 3) The mass concentrations of PM_2.5 is significantly and negatively correlated with temperature and wind speed, but positively correlated with air pressure as well as relative humidity; the correlation between PM_2.5 mass concentration and temperature can be expressed by a power function.