Abstract: To explore the rationality of the distribution pattern of park green space in the main urban area of Lanzhou, based on ArcGIS, we analyzed the accessibility of park green space in main urban areas of Lanzhou from the supply point and demand point by using Gaussian two-step floating catchment area method. The results showed that: the number of park green space in main urban area of Lanzhou was insufficient and the area was very small, the spatial distribution was quite uneven, most of the parks focused on both sides of the Yellow River in Chengguan, and green parks were deficient in Qilihe District, Shajingyi Street in Anning District, Liuquan and Xiliugou in Xigu District, Donggang Street ind Chengguan District. Overall, in 30 minutes, the service area of green space could cover most streets, but the accessibility was poor in 15 minutes. By analyzing the relationship between population density and accessibility, it is found that most of the residents live in the streets with low accessibility, and the total service quantity of the green space is inconsistent with the population density.