The invention provides a high-power intracavity frequency-doubled single-frequency laser device. The high-power intracavity frequency-doubled single-frequency laser device comprises a pumping source (5), a gain crystal (6), an annular resonant cavity, a one-way device and a frequency doubling crystal (9), wherein a first flat concave mirror (1) constituting the annular resonant cavity is plated with a film which allows base-frequency light to transmit to a certain degree and allows frequency-doubling light to transmit easily, the first flat concave mirror (1) constitutes the annular resonant cavity of the laser device on one hand, the thermal lens effect of a TGG crystal (7) constituting the one-way device can be adjusted and controlled by adjusting and controlling the intracavity power density of the laser device by means of the plated film on the other hand, and thus efficient and high-power single-frequency operation of the laser device is achieved. According to the high-power intracavity frequency-doubled single-frequency laser device, the influence of the thermal lens effect of the TGG crystal (7) on the laser device is reduced on the basis that the output power of the laser device is not affected, and thus the laser device can operate more stably on the basis that high output power can be obtained through the laser device.