Abstract: With rapid development of livestock husbandry, under situation of increasing forage planting area year by year, shorter forage harvest season, and forage nutrition loss by early or late harvesting, users should complete harvesting efficiently within a limited time, usually by means of increasing harvesting width or increasing working speed, consequently cause overload of engine, and finally resulting in shutdown of forage harvester．Aiming at above problems, an engine overload adaptive system of forage harvester was designed．The system determined forward direction of harvester through feedback signal of control handle, collected datas of engine speed and engine load percentage in real time, and started adaptive mode with one key．When engine was overloaded, controller reduced forward speed of harvester by reducing current of solenoid valve of walking pump, and engine load was reducing by correspondingly reducing feeding amount of harvester．This adaptive system could effectively reduce labor intensity and improve working efficiency of forage harvester．