Doppler frequency shift measurement is widely used in electronic warfare and radar system. Measurement in electric domain suffers from narrow range and weak electro-magnetic interference resistance. This paper proposes and experimentally demonstrates an optics-assisted Doppler frequency shift measurement approach, which employs dual-parallel Mach-Zehnder modulator for double sideband carrier modulation, band pass filtering and low-frequency photoelectric conversion in optical domain, then analyses the low-frequency spectrum in electric domain, showing an effectively solution to the disadvantages of measurement in electric domain. Experimental results shows a measurement at 7~40 GHz microwave/millimeter wave of 1 kHz~10 MHz Doppler frequency shift with measurement error of ±46 Hz.