A correction method is proposed to improve the star map simulation accuracy of splicing star simulator， which overcomes the limitation of conventional methods in improving star map accuracy merely through correcting the principal distance. The aberration of a small distortion flat field high imaging quality collimating optical system is optimized after analyzing the working principle and usage of splicing star simulator. Based on aberration design results and the star position measurement model， the correction models for distortion， coma， curvature of field are created separately. In addition， a device for measuring star position accuracy is built by utilizing the theodolite and six-dimensional adjustment mechanism. According to measurement results， the correction model based on aberration theorise effective in improving the star map accuracy of splicing star simulator. The maximum star position errorr educes from 48.78" down to 10.75"，meetting the technical requirements.