The invention relates to a wind driven generator having a speed adjusting function. The wind driven generator having the speed adjusting function comprises a tower body, a shell, a fan mechanism, a gearbox and a power generation mechanism. The gearbox comprises a variable-speed gear assembly, a leftward and rightward adjusting assembly, a PLC and a frontward and backward adjusting assembly. The variable-speed gear assembly comprises a variable-speed rotating shaft, a first variable-speed gear and an infrared receiver. The leftward and rightward adjusting assembly comprises an infrared transmitter, a bearing, a sliding block, a lead screw, fixed blocks, a first motor, a shifting block and a base. The frontward and backward adjusting assembly comprises a second motor, a round gear and a strip gear. According to the wind driven generator having the speed adjusting function, a power generation system in the power generation mechanism sends an instruction to the PLC, the PLC can move a high-speed gear in the power generation mechanism to be meshed with an appropriate variable-speed gear through a frontward and backward adjusting mechanism and a leftward and rightward adjusting structure, and it is guaranteed that the power generation mechanism is in the most stable power generation state; and, when wind force is large, the wind driven generator having the speed adjusting function can be protected.