The creep experiment of Ti40 alloy after annealing treatment at 600 ℃ for 4 h was carried on in a temperature range from 500 ℃ to 550 ℃ with various stresses. The experimental results indicate that the creep behavior can be analyzed in two temperature intervals in this creep temperature range. The first temperature interval is ranging from 500 ℃ to 520 ℃; the second one is ranging from 535 ℃ to 550 ℃. In different temperature intervals, the alloy has different creep constitutive equations. Judging by the analysis, it is deduced that the stress has obvious effect on dislocations glide and climbing controlled by heat activation when the temperature interval was at lower temperatures (500-520 ℃). With increasing temperature, the diffusion has more and more effect on the creep deformation. In higher temperature range (535-550 ℃), the creep deformation may be determined by self-diffusion or alloying element diffusion