In order to reduce the strong parallax false alarm rate of the moving target detection on a moving camera, a moving target detection method based on depth constraint equation is proposed. The relationship between twodimensional image coordinate and three-dimensional world coordinate is mainly studied. According to the image depth information and photography geometry theory, with the two frames image coordinates and the camera internal parameters, the depth constraint equation is established. The depth constraint equation includes gray value and depth information of image. Using the depth constraint equation to detect moving target can effective avoid the influence caused by moving camera. Experiments are performed based on actual image sequence, and related algorithm is compared and analyzed. Experimental results indicate that the proposed method can avoid the parallax false alarm and improve the precision of moving target detection on a moving camera is improved.