Abstract: By analyzing the reaction between matrix (Al) and inclusions (SiC) in SiC particle reinforced aluminum alloy composite under uniaxial loading, a two phase model for accumulation of diffraction elastic constants of SiC particle reinforced aluminum alloy composite was built through using self-consistent model and inclusion model. Several diffraction elastic constants of Al phase and SiC phase were figured out by the two phase model. The results calculated by the two phase model of 101 and 116 of SiC and 222 of Al are all highly coincided with test results, which give only a difference of less than 6%. And the others show difference of less than 15%. All results show the theoretical model is reliable and can predict accurately. This kind of predict model can not only avoid the tedious experiment and save the money, but also can make accurate predictions of some materials difficult to test.