Abstract: A new method for depth measurement based on defocus images was proposed. This method uses a single standard CCD camera with telecentric lens, moving camera along optical axis, images are taken at two camera position. According to the defocus radius and magnification of images, the depth is calculated. The relation between magnification and blurring can be simplified, using telecentric lens instead of traditional lens. Fusing the two disparate sources of depth information, magnification and blurring, the proposed method provides more accurate depth calculation. Experimental results demonstrate the effectiveness of the proposed method.