The invention discloses a reference synchronous circuit for resolver-to-digital conversion, which comprises a control transmission circuit, a multi-path selector and a comparator. The control transmission circuit receives a sine signal and a cosine signal which are generated by a resolver and three high bits of a resolver digital angle signal, and outputs two paths of signals A and B to the multi-path selector; the multi-path selector receives an externally input synchronization function enabling signal by a synchronization function enabling end, outputs resolver exciter reference signals REF_H and REF_L to the comparator when the synchronization function enabling signal is invalid, and outputs two paths of signals A and B to the comparator when the synchronization function enabling signal is valid; and the comparator compares sizes of two paths of input signals, and outputs a synchronous reference signal REF for providing a reference clock for a phase sensitive demodulation module so as to improve angle measurement accuracy of a resolver-to-digital conversion circuit.