Abstract: Elastic Buffers which are applied in USB3.0 and PCIE physical layer are used to ensure data integrity when bridging two different clock domains.By the research of elastic buffer mechanism and USB3.0 specification, an elastic buffer is designed by using asynchronous FIFO which has innovative function including write pointer mask,breakpoint restored,pointer jump,handshake methods and output control,and the frequency delta is managed perfectly by this elastic buffer.The width of input and output data is 10 bits,and the write clock and read clock can achieve 500 MHz.The research result can be applied to elastic buffer of USB3.0 and other system where high speed elastic buffer is needed,and is valuable to engineering application to some extent.