Abstract: To resolve the problems of large-scale and long-distance renewable energy integration in China, State Grid Corporation of China intends to build a 500 k V four-terminal VSC-based DC grid demonstration project in Zhangbei. This is the first DC grid in the world and is also the first application of the DC circuit breaker. When a short circuit fault occurs in a DC line, the station near the fault will be locked in several microseconds. Then, the DC circuit breakers trip the fault line. Overvoltage will occur at DC port of the locked station caused by charging of another DC line for its submodules. The DC overvoltage is specific in VSC-based DC grid with DC circuit breakers. This paper analyzed the DC overvoltage caused by DC short-circuit fault at sending end and receiving end in Zhangbei VSC-based DC Grid and presented its mechanism and dynamic process in detail. At the end appropriate measures were given to reduce the overvoltage.