Space close-range patrol can be used to carry out close-range observation and monitoring of targets for identifying the target′s types and working states, which is of great significance for military and civilian fields such as in orbit services. The study analyzed the general forms of space close-range patrol tasks. Furthermore, based on the optical observations of close-range patrol, the multifactor observation task effectiveness evaluation models were constructed, including a constraint model for observation, a relative distance evaluation model, an effective observation time evaluation model, and a target observation angle evaluation model. This solved the effectiveness evaluation problem for the complete process of patrol tasks, which can support the design of patrol strategies and patrol trajectories better based on the evaluation results. In addition, based on the numerical simulation analysis and semi-physical experiments, the proposed evaluation model was verified. The result shows that the actual observation effect is consistent with the model evaluation result.