The invention discloses a constant-current dimming device for an LED lamp. The device comprises a signal generator and a power converter, the input end of the signal generator is externally connectedwith dimming equipment; the output end of the signal generator is connected with the power converter, the input end of the power converter is connected with input voltage, the output end of the powerconverter is connected with the positive electrode end and the negative electrode end of the LED lamp, and the signal generator is used for receiving dimming signals of dimming equipment and then sending frequency conversion pulse signals to the power converter. The dimming range is wide, the dimming depth can reach 0.1% of rated voltage or rated current, flickering can be avoided in the dimming process and after dimming is stable, output ripples are small in the dimming process, and the power converter can use low switching frequency to achieve high conversion efficiency and output power.