Abstract: Residual thermo-strain and microcracks are the major factors which affect the behaviour of whisker toughening ceramic matrix composite materials(CMC).In this paper,the two factors are taken into account.Meanwhile,the effects of whiskers and microcracks on the effective modulus and strength of the material are researched,involving the random distribution and the content of the whiskers and the microcracks,the aspect ratio of the whiskers and the size of the microcracks.The theoretical results show that all those above factors have influence on the mechanic behaviour of the materials in different degrees.The conclusions are beneficial for the optimization of CMC.