b-value is the basic parameter of seismic risk analysis and seismic prediction, describing the distribution characteristics of the magnitude frequency relation of earthquakes of study region.Actually it is a symbol that measures the seismicity levels in a certain region, and it is widely used in seismic prediction research and seismic risk analysis both at home and abroad.In this article, several important aspects of the influence of b value statistical are discussed.We draw some conclusions and hope to facilitate seismic prediction research.First of all, we studied the influence on the b-value by calculating seismic data integrity.Based on the observation bulletins and earthquake catalogues in the north China area, we analyzed temporal and spatial variations in seismic network monitoring capability.The effect of the b value curve to inspect network monitoring ability is discussed, and the results prove that the effect with regional b value curve fitting to ensure the network monitoring ability is not reliable.As the Hebei plain seismic belt is one of main activity areas of the strong earthquakes that occurred at the third and fourth activity times in North China, and it has complicated geological structure with relatively dynamic moderate-strong earthquakes in history and modern times.So according to seismic data records in the last 44 years, based on the complete analysis of seismic sequence in the district, least square method is used to conduct time-scanning calculations of b-value, and the maximum likelihood method is used to conduct space-scanning calculations of b-value.During the scanning time, b-value is the mean b-value of research zone in every scanning window, its amplitude of variation is not quite great, with a variation range of 0.62~1.05.Space-scanning results indicate that the space distribution range of b-values basically stays within 0.5~1.4.The low b-value zone is in the Tangshan-Qian'an section and the Changping-Baodi section, consequently, b-value range 0.5~0.7, which indicates that the earth crust medium of this region is in a state of high horizontal stress accumulation and it there is a probability of a moderate strong earthquake in future.