A circuit breaker mechanism introduced in January by Liu's predecessor Xiao Gang was dismantled after only a few days. The mechanism was blamed by investors for worsening a sharp selloff in Chinese stocks.

China's Shanghai and Shenzhen stock markets slumped as much as 40 percent in just a few months last summer.

"I feel a heavy responsibility," said Liu, in his first public comments since being appointed to the CSRC last month. He was previously chairman of the Agricultural Bank of China.

Liu compared the stock market collapse last July to an oil truck losing its brakes on a downhill slope.

He said plans to shift to a registration system for initial public offerings (IPOs) of stocks would take time, requiring research and feasibility studies, technical preparations and new rules.

The CSRC has been discussing transformation of its current approval-based system -- seen as distorting the IPO market and encouraging official corruption -- to a system that would let the market decide who can list and for how much, since 2014.

China's securities regulator has come under intense scrutiny for its handling of the stock market crash, and the earlier run-up in share prices.

In February, Premier Li Keqiang offered a rare public criticism, stating regulators had not responded adequately or reacted in a timely way to the stock market turmoil.

(Reporting by Shu Zhang and Matthew Miller; Writing by Ryan Woo; Editing by Sam Holmes and Catherine Evans)