Objective: To take colorectal cancer screening project in the precinct of Gumei Community Health Service Center, Minhang District of Shanghai as the object of study, and to analyze dynamic complicity of colorectal cancer screening project in community, so that to define leverage point for implementing of colorectal cancer screening project in community and to provide a thinking tool for systematic analysis on underlying causes for poor compliance. Methods: It carried out focus group interview with first-line executives of colorectal cancer screening in community, screening data management staffs and administrator to define practical situation of colorectal cancer screening project in community. Deeply, it analyzed dynamic complicity of colorectal cancer screening project in community through systems thinking. At last, it established system model and causal flow diagram with systematic dynamic modeling software Vensim5.6. Results: Colorectal cancer screening system in community comprises governmental policy operation mechanism subsystem, community annual plan and execution subsystem, colorectal cancer screening subsystem as well as patients detection and information management subsystem. Wherein, Governmental policy operation mechanism subsystem reflects outlays and policies operation mechanism implemented by such governmental departments as health bureau for colorectal cancer screening project in community. Community annual plan and execution subsystem aims at breakdown of approaches for use of outlays as provided by the government on the execution level, which reflects community input plan and flow. As major working module in the system, colorectal cancer screening subsystem reflects the execution of colorectal cancer screening in community. Patients detection and information management subsystem serves as the rear terminal of the system, which reflects results of colorectal cancer screening. Conclusions: Propaganda of policies on colorectal cancer screening project in community, health education and free screening service serve as the important factors to encourage residents to take part in colorectal cancer screening. Meanwhile, inadequate propaganda of policies, imperfect assessment of executives and post screening service may result in decrease in screening population and poor screening compliance, which would be the critical points to be improved next in the implementation of colorectal cancer screening projects in communities in Shanghai.