The Ti/Al composite sheets were fabricated by explosive welding (EXW) and subsequent cold rolling (CR) with a reduction of 0%, 27% and 55%, respectively, then the EXW-cold rolled Ti/Al composite sheets were annealed at 600, 625 and 650 ℃ under air and vacuum environment for different time, respectively, and the annealing time was up to 576 h, finally, the effects of temperature, rolling reduction, and vacuum environment on the growth of interfacial layer of Ti/Al composite sheets were investigated. The research results are as follows. Two modifications of titanium trialuminide, TiAl3(h) and TiAl3(l) are formed at Ti/Al interface, the higher the temperature, the higher the volume fraction of TiAl3(h) phase, furthermore, the average grain size of TiAl3 phase also increases with the increase of annealing temperature. The growth of interfacial layer at Ti/Al interface can be divided into three stages: the first stage controlled by oxide films, the second stage controlled by chemical reaction and the last stage controlled by diffusion. At the stage controlled by oxide films, the growth kinetics constant is very little, and the interfacial layer thickness is relatively uniform. At the stage controlled by chemical reaction, there are some large humps at the interfacial layer, and the thickness uniformity is very low. Furthermore, at the stages controlled by oxide films and chemical reaction, the higher the annealing temperature, the larger the growth kinetics constant of TiAl3 phase. At the stage controlled by diffusion, the growth kinetics constants at 600, 625 and 650℃ are very close due to the opposite effect of grain boundary and temperature on the interdiffusion coefficient of TiAl3 phase. Furthermore, the thickness uniformity of interfacial layer increases with the extension of annealing time at different temperature, and the higher the temperature, the higher the thickness uniformity at the same annealing time. At 600℃, cold rolling can improve the growth rate and thickness uniformity of TiAl3 phase at chemical reaction-controlled stage and the beginning of diffusion-controlled stage, and the bigger the reduction, the bigger of growth rate and thickness uniformity. However, at 650℃, cold rolling has little effect on the growth rate and thickness uniformity of TiAl3 phase at chemical reaction-controlled and diffusion-controlled stages. At the stage controlled by oxide films, the growth kinetics constant under vacuum environment is larger than that under air environment, at the chemical reaction-controlled and diffusion-controlled stages, the growth kinetics under vacuum environment is almost same with that under air environment, but the thickness uniformity of TiAl3 phase under vacuum environment is higher than that under air environment.