To reduce the current unobservable region within the spatial voltage vector synthesis region and increase the output voltage modulation ratio， a strategy of three-phase current reconstruction for single resistor sampling with high modulation ratio is proposed. The switching state phase shift process is divided into three stages according to the difference between the switching state and actual hardware sampling delay， and the process with difference switches is carried out， which increases the output voltage modulation ratio without any modification of the original circuit topology. The currents are sampled during the first half Pulse Width Modulation （PWM） period and reconstructed in the second half PWM period. Meanwhile， it fully utilizes the turn-on time of the zero vector， reduces the unobservable area， and realizes the complete reconstruction of the three-phase current. Finally， the feasibility and effectiveness of the strategy are verified by simulations and experiments.