The application provides a dispersed carrier phase-shifting method and system. The method includes connecting at least two power modules to form a modular system; each power module including a control module for sampling at least twice a common state variate, signs of slopes of the common state variate at a first and second sampling time are opposite, and a reference time of the first sampling time for each control module is the same; and regulating a carrier frequency of the power module according to a relative size between a sampled values at the first and second sampling time. According to embodiments herein, carrier phase-shifting of modular system may be implemented without communication between respective modules. Under closed-loop control, optimal carrier phase-shifting can be automatically achieved under various duty ratios, thereby having good stability.