Effects of heat treatment processing on the microstructure and mechanical properties of Ti-6Al-4V-10Nb alloy were investigated. The microstructures were investigated by SEM, TEM and XRD, and the mechanical properties were evaluated by tensile tests at room and elevated temperatures. The results indicate that the lath-like and globular primary alpha phase, secondary alpha phase and beta phase are obtained after forging and heat treatment processing. The size of secondary alpha phase is much smaller than that of primary alpha phase. After heat treatment, the volume fraction of primary alpha phase is decreased, and that of secondary alpha phase is increased. With the increase of solution temperature, the volume fraction of primary alpha phase is gradually decreased, and that of secondary alpha phase is obviously increased. The yield strength and tensile strength of Ti-6Al-4V-10Nb alloy are significantly enhanced with the solution temperature increasing.