Characteristic of α phase is an important factor affecting the mechanical properties of titanium alloys. To predict the microstructure evolution of the Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr) with initial lamellar α, the dynamic globularization kinetics model of Ti-55531 during hot deformation was characterized by Avrami equation. A series of thermal simulation experiments were conducted to obtain the curves of stress σ versus strain ε to determine the equation parameters. By further transforming the stress σ-strain ε curves into strain hardening rate dσ/dε-ε curve, the critical strain εc (corresponding to the minimum value of dσ/dε) and the peak strain εp (the strain at dσ/dε = 0) be obtained. The dynamic globularized fraction fg at different deformation conditions was also measured. Sequentially, the parameters in the Avrami equation were determined from the linear fitting of the relationships among strain rate, temperature, and dynamic globularized fraction. The as-obtained Avrami equation was expressed as fg =1-exp[-0.5783((ε-εc)/εc)0.907], where εc =0.6053εp and εp =1.249×10-4?0.0807exp(58580/RT). Finally, the as-obtained dynamic globularization kinetic model was implanted into finite element program to simulate dynamic globularization kinetics. By combining the dynamic globularization kinetics model with the finite element method, the dynamic globularization of the lamellar α was predicted effectively.