The invention belongs to the technical field of analog-digital converter, and in particular relates to a source electrode follower buffer circuit. The circuit comprises a first NMOS transistor M1, a second NMOS transistor M2, a first PMOS transistor M3, a second PMOS transistor M4, a first current source I1, a second current source I2, a fully differential operational amplifier and a common-mode voltage feedback module, wherein the M1, M2, M3 and M4 always work in a saturation area, source electrode voltages of the M1 and M2 follow the change of VN and VP, an input pair transistor substrate is in short circuit with the source electrode and thus the bulk effect of the transistors is eliminated, a feedback loop formed by the fully differential operational amplifier under a large-swing input signal provides stable static working points for the M1 and M2, when a load is connected with the output end, the feedback loop help the transistors M1 and M2 charge and discharge, current change of the transistors M1 and M2 is reduced, and the linearity of the follower is improved. According to the circuit provided by the invention, the bulk effect and the channel length modulation effect are avoided, current change in the transistor in the follower is greatly reduced, and the circuit has the advantage of high linearity.