In order to optimize the performance and volume of the medium-range laser triangular displacement sensor, a mathematical model was established to optimize the structural parameters with the 200 mm~500 mm range as an example. In the structural design of the sensor, a plane mirror was used to fold the optical path, and the objective function was defined with the working object distance, lens focal length, linear array detector position and mirror position as the optimized parameters, gravitational search algorithm (GSA) was used to optimize the structure of the displacement sensor. After the algorithm iteration, compared with the traditional laser triangle structure with the same width limit, the sensitivity of the optimized structure was increased by 24.29% at 500 mm, and the nonlinear error was reduced from 11.40% to 7.43%. The results show that this structure and optimization algorithm have a positive effect on the performance and volume of the laser triangular displacement sensor.