In order to solve the problem that vertex and bottom points of the crop are difficult to be identified in height measurement of crop by using the visual method, a crop height measurement system based on laser vision was designed. The improved triangulation model, which was designed according to the character of crop height measurement, was used to describe the mathematical model of the system. The model parameters of the crop height measurement system included three parts, which were the parameters of camera, the equation of light plane and camera installation parameter. The model parameters were calibrated by a novel checkerboard method. In the process of the system parameters calibration, the checkerboard must be placed on the parallel plane of the corresponding horizontal plane where the bottom point of the crop was on at least once，to establish the ground coordinate system. Furthermore, the system identified the crop apex by projecting the laser onto the crop. The results of measurement in crop plant height of 558.00~1843.30mm showed that the absolute error was no more than 28.30mm and the relative error was no more than 2.17%. Furthermore, the restrictive conditions of the system and suggestions for engineering implementation were given. This system can achieve real-time measurement automatically with a high precision and it had good practical value.