Abstract：In the hot dry rock(HDR) extraction，according to the rock mineral compositions and different distributions，the thermal dilatability is considered as random medium. With the plane stain model，the random non-homogeneous solid-heat coupled mathematical model and stress field are established，and the FEM coupling is achieved. With the two random distributions of Gauss distribution and Weibull distribution，based on a variety of numerical experiments of the HDR extraction，the characteristics and laws of temperature，stress fields，and the derived results reveal that the random distributions of thermal dilatability have great influences on thermal fracture law，the relationship between temperature and time，the relationship between crack ratio and time，and the plane maximum main stress distribution.
