The invention discloses a melt impregnation device for reducing fiber breakage rate. The melt impregnation device comprises a lower template, an upper template and a flow channel height automatic regulating device. The lower template and the upper template are enclosed to form a curved flow channel melt chamber. The flow channel height automatic regulating device is used for regulating height of the curved flow channel melt chamber to fit different fiber movement velocities and melt flow velocities and eliminate a shearing field inside the curved flow channel melt chamber. According to parameters such as output, bars hauling speed, width of the curved flow channel melt chamber and the like, under the condition of guaranteeing no overflow, breakage rate of fiber in the impregnation device can be reduced, and productivity and production quality of prepreg are greatly enhanced. A reasonable height of the curved flow channel melt chamber can be rapidly and accurately regulated according to different production requirements, repeated exchange of the device is avoided, and production efficiency is raised.