Abstract: Based on the current using velocity model of Hebei Seismic Network, the range of earthquake distance that the Pb phase can be found is calculated with travel time equation. The blind zone of Pb phase is about 70 km, and the range of initial epicentre which the Pb phase can be found as the first phase is from 90 to 120 km, and the range of initial epicentre which the Pb phase can be found as the later phase is from 135 to 150 km. 88 seismic waves were collected in this article to recognize Pb phase according to the theoretical waveform characteristics and the time comparison between the theoretical and actual waveform. Finally 158 effective Pb phase were recognized, and the velocity of Conrad discontinuity is 6.69 km/s,the depth of Conrad's discontinuity is 21 km. We summarize the actual waveform characteristics of Pb phase in Hebei area and make up for the blank of Pb phase of Hebei Seismic Network. Based on the radiation distribution of Pb phase,it is found that Conrad's discontinuity developed well in the mountainous area of northern Hebei, followed by the South, and the least continuous area in the central Bohai Bay basin.