In order to meet the demands of renewable energy resources intake and power quality enhancement of distributed generation systems, the key technologies of the multi-functional grid-tied inverter (MFGTI) with power quality management function were studied. To address the problems of low precision of compensation current detection method and poor tracking effect of control method in traditional control scheme, an integrated control scheme based on improved sliding mode control was proposed. Firstly, the mean value algorithm was introduced into the harmonic and reactive power detection method based on the Fryze-Buchholz-Depenbrock (FBD) power theory to improve the accuracy and response speed of the compensation current detection, so as to enhanced the accuracy of command current. Then, based on the sliding mode control (SMC) and the mode predictive control (MPC), the MPC-SMC strategy was proposed, which further improved the high precision and fast tracking control performance of the MFGTI for the complex reference current. Finally, based on MATLAB/Simulink, the proposed control scheme was verified through simulation under different conditions. The results confirm the effectiveness and feasibility of the proposed control strategies.