The invention relates to a data synchronization method used for analog-digital mixed recording. The method includes the steps that (1) time of an analog-digital mixed recording device and time of a merging unit are synchronized; (2) an alternating current analog signal source respectively sends analog signals to the analog-digital mixed recording device and the merging unit; (3) the received analog signals are sampled to obtain a plurality of sampling signals, and a local time label is loaded for each sampling signal; (4) according to an external order, of steady state recording and transient state recording, which is to be carried out is judged, if the steady state recording is to be carried out, a step (5) is carried out, and if the transient state recording is to be carried out, a step (6) is carried out; (5) the two identical time labels are aligned, and synchronization of the analog signals and digital signals is achieved and completed; and (6) two catastrophe points with the same gradient are aligned, and the synchronization of the analog signals and the digital signals is achieved and completed. Traditional interpolation synchronization is eliminated, a sampling value is not changed, and a minimum phase angle amplitude error is achieved.