Ground-based photoelectric detection system is an important detection method for signal acquisition of space targets, and exposure time is the main parameter affecting its detection performance. Based on the optical properties of the space target, limit detection distance, minimum detectable size and limit detection star of the system are calculated, and the quantitative relationship between the exposure time and other influencing factors is analyzed. Combined with the image shift model of the space target, the relationship between the system detection ability and the exposure time under dynamic conditions is obtained, and a simulation study is conducted. The results show that the system detection capability increases with the exposure time and becomes stable when the target is relatively stationary. When the target is in relative motion, the system detection capability increases firstly and then decreases with the extension of the exposure time, and there is an optimal exposure time related to the target relative angular velocity. The simulation results can provide optimization feasibility for the exposure time setting of ground-based photoelectric detection system.