Abstract: With the growth of population and the degree of urbanization become more and more high，as one of the urban land use types，the nature and the use of public green space is most easily changed. Carrying out the value evaluation of urban public green space，it is an urgent problem to be solved in the current urban planning，green space protection and construction. This paper reviews the main problems existing in the public green space of the three provincial capitals of Gansu，Qinghai and Ningxia as typical cities of urban agglomeration in the western area，and evaluations the services value of urban public green space by means of CVM. The research shows that total value of ecosystem services provided by the public green space in Lanzhou is about 33 240-37 610 thousand; analysis the influence of social factors on the willingness to pay，the positive effect of occupation，income，gender and other variables on the willingness to pay is relatively large; Xining and Yinchuan，because of the scale of city is relatively small，the total value of ecosystem services provided by public green space is slightly lower than Lanzhou， comparison ecosystem services value output of unit public green space area can be found， the output of ecosystem service value of unit public green space area in Lanzhou up to about 1.57-1.77 yuan/m²， output efficiency of ecosystem services value in Lanzhou public green space is relatively high.