Due to the limitation of the breaking capacity，speed and cost of the DC circuit breaker，the DC power grid faces the problem of fault isolation. This paper proposes a hybrid fault current limiter （FCL） based on commutation capacitors. After fault，the current limiting branch will be put into the fault loop by commutation capacitors to suppress the fault current. The current limiting branch consists of thyristor，commutation capacitor，current limiting resistor and current limiting inductor. In this paper，the topology structure of the current limiter is given，and its current limiting principle in different stages of the fault is analyzed； Kirchhoff's law is used to list the loop equations of the commutation capacitor in different stages，and the current limiting effects under different parameters are theoretically analyzed so as to be the theoretical basis for parameter design. The four-terminal DC power grid model is built in PSCAD/EMTDC to verify its current limiting effect. The simulation results show that the proposed FCL can effectively slow down the discharge speed of the sub-module capacitor，so that the rising rate of short circuit current at 5 ms after the fault decreases from 2.254 kA/ms to 1.015 kA/ms，the increase of fault current is effectively suppressed and the breaking capacity of the DC circuit breaker is reduced.