The invention provides a large-aperture crystal frequency-doubling conversion device realizing crystal temperature regulation and control under forced convection, relates to the large-aperture crystal frequency-doubling conversion device, and aims to solve the problem that an existing heating device fails to realize precise temperature control over a large-aperture crystal and maintain relatively high temperature surface uniformity of the crystal. The large-aperture crystal frequency-doubling conversion device comprises a supine micro-driving mechanism and a deflecting micro-driving mechanism. The large-aperture crystal frequency-doubling conversion device further comprises a box body, a total water inlet pipe, a total water return pipe, a constant temperature water tank, a control valve, a large-aperture crystal frequency-doubling mechanism and two fans. The box body comprises a first box body, a second box body, a side wall end cover and a light-transmission end cover. The first box body and the second box body are identical in structure and are respectively open on two ends. The large-aperture crystal frequency-doubling mechanism is installed in the inner cavity at the connection part between the first box body and the second box body. The two fans are installed on vertical inner walls of the box body in an opposite manner. A cavity rectangle frame body is internally provided with a box body temperature control channel. The large-aperture crystal frequency-doubling conversion device is used for realizing frequency-doubling conversion of a large-aperture laser.