The invention belongs to the technical field of tunable lasers and particularly relates to a method for widening a tuning range of a full-solid-state continuous wave single-frequency laser. The methodis simple and easy to operate and capable of effectively widening the tuning range of the full-solid-state continuous wave single-frequency laser. The method for widening the tuning range of the full-solid-state continuous wave single-frequency laser comprises the following steps that 1, a nonlinear frequency doubling crystal is plugged into a laser resonant cavity; 2, the nonlinear frequency doubling crystal converts a part of in-cavity base-frequency light into frequency-doubling light, the produced frequency-doubling light and the base-frequency light are output together from the laser resonant cavity and are separated through a spectroscope; 3, a part of the base-frequency light reflected by the spectroscope is separated out through an optical beam splitter, and the residual part serves as main laser to the output; 4, the cavity length of the laser resonant cavity can be changed by regulating the voltage loaded on piezoelectric ceramic in the full-solid-state continuous wave single-frequency laser, and thus continuous tuning of the output frequency of the full-solid-state continuous wave single-frequency laser is achieved.