Provided is an ARTM CPM demodulation and synchronization method with low implementation complexity. The method comprises, firstly, performing a two-stage delay on a received signal to obtain three branch signals; then performing mixing, low-pass filtering, matched filtering and phase compensation processes on the three branch signals, and performing Viterbi demodulation processing on the I-branch signal, and then calculating a timing error and a carrier phase error using a demodulation processing result; and finally, adjusting a code NCO and a carrier NCO by using a filtering result of the timing error and the carrier phase error, so as to achieve symbol timing synchronization and carrier phase synchronization. Compared with the existing optimal demodulator, the method of the present invention has less loss of bit error performance, and the numbers of matched filters and states required for demodulation are greatly reduced, thereby the demodulation complexity can be greatly reduced and the system stability can be effectively improved.