The engineering problems brought by the contradiction between the bad physical nature and good mechanical properties of red clay are drawing more concern in the academic and the engineering circles. Making use of ionic soil stabilizer(ISS) can effectively change the physical properties and mechanical performances of red clay in Hanyang district of Wuhan City. In order to study the phase composition and the spacing of crystal plane of red clay reinforced by ISS, the X-ray diffraction of red clay was done under the conditions of Mg2+ -saturated, K+ -saturation, glycerol-saturation and heating to 550 ℃ by the Siemens D5000 X-ray diffractometer. The results showed that the phase composition of red clay reinforced by ISS has not significant variation, and the spacing of crystal plane has a small change.