This paper summarizes computer technologies in green city constructionin western China, which includes risk assessment and early warning of geological disasters, ecological city planning and infrastructure construction, and green building structure system. In the risk assessment and early warning of geological disasters, GIS technology is applied together with remote sensing technology to acquire basic information of large-scale geological hazards, which is in favor of monitoring and early invention of hazards. In the ecological city planning and infrastructure construction,the earthwork analysis and land use evaluation with GIS technology, the regional traffic simulation with Transcad technology, the wind environment simulation with CFD technology and the sunshine simulation with Zhongzhi software are gradually given attention and further applied. In the green building structure system, finite element numerical method and parallel computing are playing important roles in seismic analysis of civil engineering structural systems.