In order to explore the effect of cryogenic treatment on the microstructure of different titanium alloys， three titanium alloys，TA7，TA6 and TC4，were immersed in liquid nitrogen tank （-196℃） for cryogenic treatment （DCT）.Electron microscopy （SEM） and X-ray diffractometry （XRD） were used to analyze the microstructure changes of titanium alloys before and after cryogenic treatment.XRD analysis results show that the intensity of the diffraction peak lines of TA7 and TC4 is significantly increased after cryogenic treatment，while the intensity of the diffraction peak lines of TB6 before and after the experiment is different，indicating that obvious lattice distortion occurs in the samples of TA7 and TC4.The lattice spacing of the three materials changes after the experiment， indicating a change in grain size.The SEM analysis results show that the cryogenic treatment can refine the microstructure of all three materials and enhance their density.Additionally， the number of precipitates in the TA7 and TC4 titanium alloys increases.Therefore，cryogenic treatment can effectively optimize the microstructure of titanium alloy.