A high-dynamic and high-precision ranging system based on laser phase-shift ranging was studied.The optical frequency modulation technology was introduced in system to realize laser beat-frequency, produce high-frequency modulation signals and complete the rapid-change measuring tape modulation of signal.In the phase demodulation of echo signal, the windowless all-phase spectrum analysis was adopted and the phase calculation of measuring signal was realized for the purpose of reducing the phase demodulation deviation.The calculation shows that the proposed method can effectively retrain spectrum leakage, reduce the influence of noise on the measurement results, and improve the phase demodulation precision.The experiment shows that this ranging system can effectively solve the problems such as poor anti-jamming capability and difficult mitigation of range ambiguity in the phase ranging.The ranging precision is more than 0.5 mm when the modulating signal frequency is 100 MHz and SNR is 30 dB.