A memory test system for peak power reduction. The memory test system includes a plurality of memories, a plurality of memory built-in self-test circuits and a plurality of delay units. Each of the memory built-in self-test circuits comprises a built-in self-test controller for receiving a clock signal and producing a plurality of required control signals to test one of the memories. Each of the delay units is coupled between two adjacent built-in self-test controllers. The clock signal input to one of the built-in self-test controllers is received by the delay unit to produce a delayed clock signal, and the delay unit outputs the delayed clock signal to the other.