Modular multilevel converters(MMC) can be used in many applications such as medium voltage multi-megawatt drives and HVDC power transmission. Modulation strategy plays an important role for the good performance of MMC. In this paper, a submodule(SM) regrouping method of MMC is presented and based on this, a sampling time staggered space vector pulse width modulation(STS-SVM) technique is proposed for MMC. Each group has three SMs, which is irrespectively from three phases. Thus, the SVM scheme for the two-level converter can be applied in each group. For an MMC with n-SMs per arm, the two-level SVM for each group is staggered evenly over the sampling time, so as to achieve an equivalent switching frequency at the output. Therefore, the STS-SVM can be very easily expanded with the increasing of the SMs number, and also, the off-line or on-line effort/tasks about generating the SVM switching sequences are simplified significantly. Besides, the capacitor voltages of SMs can be balanced by rotating the gate signals of different SMs even without any capacitor voltage detecting or sorting because the even power distribution among SMs is realized. A three-phase MMC is simulated at both steady and dynamic states in MATLAB/Simulink and validate the performance of the proposition.