With the increasingly serious environmental pollution and stricter emission standards, energy saving and emission reduction in construction machinery (CM) are imminent. Electrification of CM is an inevitable trend. Due to the complicated working conditions and the violent load fluctuations, the existing motor controller cannot adapt well to the operating characteristics of the electric CM. In this paper, the work requirements of the positive flow system are analyzed. Considering the robustness and resistance to load disturbance of the control system, a vector control strategy through online tuning of speed PI parameters based on fuzzy control is proposed. The characteristics of the control system are analyzed with the co-simulation of AMESim and MATLAB/Simulink. A test rig was set up to verify the feasibility of the control strategy. The results show that when the load is variable, the fluctuation of rotation speed is approximately 1.5% with fuzzy PI, and 2.5% with traditional PI. Furtherly, the vector control algorithm based on fuzzy PI is tested on a positive flow system. The test results show that when the load fluctuates drastically, the electric motor speed fluctuation is within 3.5%, and the steady-state error is only approximately 0.3%.