A timing oil-control method for driving an engine brake comprises a timing oil-control process using a timing oil-control mechanism to control oil supply time or oil discharge time of the engine brake. The timing oil-control mechanism comprises a timing oil way and a timing valve system. The timing oil way connects a brake oil supply valve of the engine brake with the timing valve system. The timing valve system controls time or the phase of oil charge or oil discharge of the engine brake. The timing oil-control process comprises the following steps that firstly, the brake oil supply valve is connected; secondly, the timing valve system is connected during a certain time or phase in the engine period; and finally, the engine brake is subjected to oil charge or oil discharge. Timing oil supply or oil discharge is provided for the engine brake, the randomness of starting or shutdown of a traditional engine brake is eliminated, and the reliability and durability of a brake mechanism and an engine are increased.