Synthetic seismic record calibration is the basis of structural interpretation and reservoir prediction.The accuracy of synthetic seismic record calibration directly determines the accuracy of subsequent structural interpretation and reservoir prediction,and only when the polarity of the corresponding seismic section is accurately determined,the calibration can be accurate.Therefore,determining the polarity of seismic data is the most basic work.In practical production applications,the conventional method which uses the positive and negative polar waves to produce the synthetic seismic records and then compare the correspondence between the two and the seismic trace often fails to determine the polarity of the seismic profile.In this paper,the polarity determination of the Sulige gas field was taken as an example and,according to the principle of phase scanning,the forward modeling and formula derivation were conducted.The results show that the phase of the seismic profile and phase correction quantities are opposite.In the actual data analysis,the phase correction can be obtained by using the phase scanning to compare the well impedance and the relative impedance of the seismic traces nearby the borehole,and then the phase of the actual seismic profile can be obtained to determine the polarity of the seismic profile.The method is intuitive and has good operation and popularization in practical application.