The invention relates to a time difference ranging radar structure with low power consumption and simple structure, and belongs to the technical field of radar structures and radar ranging. The structure comprises a digital gradient generator, a digital control type oscillator, a power amplifier, a transmitting and receiving antenna, a low-noise amplifier, an envelope detector and a time-to-digital converter. The time difference ranging radar structure can solve the problem that the radar resolution of a frequency modulated continuous wave radar is seriously limited by bandwidth, meanwhile, anoscillator in a transmitter part is controlled by an enable signal, and when a multi-bit digital signal is input, the oscillator only works in a half cycle that the multi-bit digital signal is in anupward gradient, so that the power consumption is greatly reduced; in the receiver part, the demodulation and measurement circuit part adopts an envelope detector to detect the envelope of an echo signal, and adopts a time-to-digital converter to measure the time difference, so that compared with a coherent demodulation and frequency difference measurement method of a frequency-modulated continuous wave radar, the structure is simple.