The alignment errors affect the imaging quality of optical system. We analyze the influence of eccentric error in the high-resolution optical imaging system. Based on a self-designed high-resolution spaceborne optical system which is closed to the diffraction limitation, we use the software Zeamx to analyze how the decenter and tilt during its alignment process affect the MTF.At the same time, we know that the weight of separate element affects the optical system. It can provide the basis for the design and implementation of alignment, and achieve the high-resolution imaging of 25 million pixels. This error analysis method can control the alignment effectively and improve the efficiency of system alignment.