A forward image displacement compensation device is designed and its feasibility for area scan color CCD airborne mapping camera is researched to improve the ground pixel resolution and the mapping accuracy. The effect of intrinsic and extrinsic parameters on image point during forward image displacement compensation is emphatically analyzed based on imaging relation of central projection, and the feasibility of the forward image displacement compensation for airborne mapping camera is verified. The compensation device, which is based on constant-diameter conjugate cam is designed and factors′ affecting the accuracy of aerial photogrammetry are studied. The rectified method is proposed by using affine transformation. Experimental results show that the rectified accuracy is 0.001 mm, and the proposed method of forward image displacement compensation is correct.