The invention discloses a method for detecting a spatial weak moving target, for solving the technical problem that the traditional method for detecting a spatial weak moving target is low in detection ratio. The technical scheme is that a moving target is detected by using a method combining the target track continuity with the characteristics such as target gray level, background constitutive property, and the like; in an image pretreatment stage, the effect of noise is effectively eliminated by cutting based on the gray level and area; in a detection stage, the target moving continuity characteristic between two frames is utilized to effectively eliminate the quasar interference, and the problems that the processing efficiency is decreased by accumulating multiple frames in order to eliminate the quasar and the quasar background cannot be removed under the influence of background illumination and noise are solved; the whole target track is finally treated and the false target is removed; and the lost target is filled. When the signal-to-noise is less than 3, the detection ratio is increased to above 95% from the detection ratio below 90% in the prior art.