China Securities Regulatory Commission Chairman Xiao Gang addresses the Asian Financial Forum in Hong Kong.
Xiao's departure comes just a month after the CSRC denied reports he had offered his resignation.
He was the architect behind China's circuit breaker system that was heavily criticized when the Shanghai Composite suffered heavy losses at the start of 2016.
China's stock market is down about 45% from its June peak and 19% so far this year.
Liu Shiyu, the current chairman of the Agricultural Bank of China, and a former deputy governor of the Chinese central bank, will replace Xiao, according to the WSJ.