A slew rate control circuit is disclosed. An output impedance buffer and a slew rate buffer are coupled in parallel. An edge detector detects an input signal to accordingly control the output impedance buffer and the slew rate buffer, such that the input signal passes through the slew rate buffer during a rising or falling time period, and the input signal only passes through the output impedance buffer during a stable time period, thereby conforming to specification requirements for the slew rate and the output impedance at the same time.