Aiming at the problems of traditional laser elevation control technology, low control accuracy and poor adaptability of farmland pipe laying equipment, an elevation control system of trenchless pipe installation machine based on RTK-BDS was designed. The system was mainly composed of elevation detection system and elevation control system. The elevation detection system took RTK-BDS as the core, combined with the middle frame structure, used acceleration sensor, pulled wire sensor and other sensors, and adopted the multi-sensor information fusion algorithm of multi-model UKF to obtain high-precision altitude information;the elevation control system mainly controlled the height of the plow through the proportional valve control oil cylinder, and through the analysis of the mathematical model of the elevation oil cylinder control, the design was completed. The multi-mode fuzzy PID control algorithm was used to control the expansion and contraction of the oil cylinder, so as to realize the working requirements of the plow according to the specified slope index. Through the static test, UKF, particle filter and multi-model UKF algorithm were used to detect the elevation information. The test showed that the filtering effect of multi model UKF algorithm was better, and the maximum relative detection error was 0.181cm, and the average relative error was 0.051cm. In the dynamic situation, the tracking effect was better and the relative error was smaller. Through the field test, the elevation control experiment without slope, the elevation control experiment with slope and the comprehensive experiment were carried out. The results showed that the elevation control error can be kept within ±2cm, which can meet the requirements of pipe laying by trenchless pipe laying machine.