Abstract: In view of problem of signal integrity of transmission line in high-speed circuit system, the paper gave reasons of reflection phenomenon produced in signal transmission through analysis for equivalent circuit of transmission line on PCB of high-speed circuit. It introduced common methods of eliminating the reflection, namely selecting uniform transmission line, using proper topology of wiring and impedance matching method, and indicated that the impedance matching method can solve the reflection phenomenon in signal transmission, and expounded principles of eliminating the reflection and applicable condition of impedance matching method of source-end and impedance matching method of load-end. In view of reflection problem in clock circuit, the paper used PADS/Hyperlynx software to make simulation for the impedance matching method, the result shows that the impedance matching method can improve the reflection phenomenon in signal transmission.