Abstract: In order to improve the fuel efficiency of agricultural tractor engine, this study designs a load-sensitive engine speed control system, and the engine speed controller is designed and optimized by using a tractor simulation model. The average error range of tractor model simulated engine speed and torque value is ≤5.0%, the error range of control system on tractor speed control is ≤1.17%, the engine fuel efficiency indexes of unit volume fuel consumption（SVFC）, unit tillage area fuel consumption（FCA） and fuel consumption per working hour（FC） are 23.0%～ 57.9%, 4.1%～42.1% and 7.2%～38.5%, respectively, which were significantly improved compared with the conventional tractor engine. The results of the study provide theoretical reference and technical support to optimize the tractor engine control algorithm and improve the fuel efficiency of the tractor.