We propose a high-precision attitude angle measurement system utilizing laser collimation to rectify environmental errors that significantly impact the precision of high-accuracy star sensors. Environmental factors, primarily temperature variations, can induce shifts in the optical axis of star sensors deployed in orbit, leading to errors in attitude angle measurements. Leveraging the conventional star sensor architecture, we have augmented the system with an additional laser path and a four-quadrant detector (4QD) positioned in the image plane. This setup converts angular deviations of the optical axis into positional shifts of the laser spot, facilitating the measurement of environmental errors. Both simulations and experimental findings demonstrate that the laser collimation system effectively mitigates environmental errors, thereby enhancing the attitude accuracy of the star sensors.