The retracing behavior of the phase‐matching angle (RBPA) of many nonlinear optical crystals in optical parametric oscillators (OPO) is reported here. The wavelength range of the pump wave and the tuning angle range over which RBPA can occur are obtained. Furthermore, the generality of this novel and interesting phenomenon is successfully explained by theoretical analysis. We point out that RBPA exists generally in both type I and type II OPO’s by using either uniaxial or biaxial crystals.