In order to achieve miniaturization of the laser displacement sensor structure, a single-mirror reflective laser displacement sensor structure is used. Sensitivity, working distance, and system structural parameters of this structure are optimized through research. Initially, a single mirror is used in this structure to deflect incident light in the direction of the laser, widening the optical path within the sensor to improve spatial utilization. Subsequently, a genetic algorithm is employed to optimize the design of the sensor's structure, obtaining the optimal parameters under specific constraints. Finally, an appropriate imaging system is designed for validation. The result indicates that, compared to traditional laser displacement sensor, the single-mirror reflective structure can reduce the sensor's longitudinal dimension from 55. 9mm to 31. 0mm while maintaining sensor sensitivity and working distance. This suggests that the introduction of the mirror effectively reduces the sensor's size. This conclusion holds significance for the miniaturization design of laser displacement sensor.