Actuator rate limiting is the primary course of Aircraft Pilot Coupling (APC) for fly-by-wire (FBW) aircrafts. To avoid APC with minimum cost, the rate limiting boundary determining method is proposed based on the Pilot Vehicle System (PVS) closed-loop stability requirements. The actuator rate limiting is modeled by describing function. The relationships between actuator rate limiting, APC onset frequency and PVS closed-loop stability are analyzed. On the basis of this, an actuator rate limiting boundary determining method is proposed. A Relaxed Static Stability (RSS) aircraft is taken as an example, based on the optimized McRuer pilot model, the longitudinal actuator rate limiting boundary that can ensure the closed-loop stability is determined. The OLOP criterion evaluating results shows that the determined actuator rate limiting boundary coincides with the actuator rate corresponds to OLOP criterion boundary, indicating that the proposed rate limiting boundary determining method is reasonable.