Abstract：Based on its morphological characteristics, this paper made a preliminary analysis of the genesis of the Ordovician gypsum-bearing breccia in North China. The geothermal characteristics during the formation stage of the gypsum-bearing breccia were analyzed with the numerical method, and the results show that the temperature condition for the dewatering of clay minerals and gypsum did exist. The pore gas pressure of gypsum-bearing mudstone at high temperature was analyzed with the experimental method, and the result shows that extremely high pore gas pressure will be generated by gypsum dewatering at high temperature. The SEM and energy spectrum analysis show that the mineral structure of gypsum is changed at high temperature. It is thus held that the gypsum-bearing breccia in North China might have been generated by air burst.