The invention discloses a bidirectional buffer circuit for two-wire serial interfaces, and relates to the field of analog integrated circuit design. The bidirectional buffer circuit comprises a bus master, a bus slave and a bidirectional buffer, wherein the bus master comprises a master data bus SDAM which is connected with a power supply VDM through a pull-up resistor RM and grounded through a stray capacitor CM; the bus slave comprises a slave data bus SDAS which is connected with the power supply VDS through a pull-up resistor RS and grounded through a stray capacitor CS; the bidirectionalbuffer comprises a buffer BUF1, a BUF2 and a switch signal CNCT; both output of the buffer BUF2 and input of the buffer BUF1 are connected with the master data bus SDAM when being connected with eachother; both output of the buffer BUF1 and input of the buffer BU2 are connected with the slave data bus SDAS when being connected with each other; and the switch signal CNCT is used for controlling the opening and closing of the buffer BUF1 and the buffer BUF2. According to the bidirectional buffer circuit, when bus wiring distances are relatively long or slaves connected on buses are too many, the bus signal quality is not influenced.