In order to study the influence of hydrogen on the high temperature deformation behavior and microstructure evolution of 45Ti-47Zr-5Al-3V alloy, a dynamic thermal simulation machine was used for the as-cast alloy with and without hydrogen under different deformation conditions. The flow stress and deformation activation energy of TiZrAlV alloy can be significantly reduced by adding proper amount of hydrogen. The activation energy of unhydrogenated and hydrogenated alloy is 339.7 kJ/mol and 286.5 kJ/mol. Meanwhile, the optimum thermal processing parameters are 700-900℃, 0.01-1s-1. The OM and EBSD microstructure observations show that adding hydrogen can refine the as-cast structure, increase the β-phase content and promote dynamic recrystallization, thus significantly reducing the flow resistance of the alloy, expanding the hot processing window and improving the thermal processing performance.