The invention discloses a 
voltage-sharing and power-sharing control method of a single-phase multi-module cascading 
solid-state 
transformer. A power main circuit part of the single-phase 
solid-state 
transformer is composed of an AC / DC rectifying input stage, a DC / DC middle stage and a DC / AC output stage. The rectifying stage and the middle stage serve as a 
system for controlling and designing, a common duty ratio control strategy based on single-phase d-q 
vector control is adopted in the input stage, the output direct 
voltage of the middle stage serves as feedback quantity of an outer 
voltage loop, the stability of the output direct voltage of the middle stage is achieved, and a unity 
power factor of an input end of a 
power grid is achieved; a control strategy based on voltage feed-forward and voltage feed-backward is introduced into all modules in the middle stage at the same time, the voltage feed-forward serves the benchmark of the voltage feed-backward, and errors of the voltage feed-forward and voltage feed-backward serve as the benchmark of a module current 
inner loop after being output by a voltage 
PI regulator. The front stage control strategy is interacted with the middle stage control strategy, and therefore the purposes that voltage and the power of modules of an SST are balanced, the 
power grid side unity 
power factor is achieved, the 
power grid current sine degree is high, the voltage stress of a switch tube is low, and the 
ripple of the output direct voltage of the middle stage is low.