Influence of low temperature aging on phase transformation behavior and mechanical properties of Ti-10V-2F2-3Al alloy has been investigated. Results show that isothermal ω particles and α″ martensitic plates are continuously formed in the β matrix with increasing aging time. When the aging time is more than 4h, ω particles gradually disappear and lots of isothermal martensites are still produced. Tensile testing shows that, the 0.5h-aged specimen has the highest plasticity and lower yield strength than the rest specimens. With increasing aging time, plasticity is decreased sharply and strength is increased rapidly. However, plasticity is recovered slowly and strength is increased continuously once the aging time is more than 4h. Comprehensive analysis indicates that good plasticity in the 0.5h-aged specimen is attributed to transformation-induced plasticity effect (TRIP) during tensile process; Embrittlement induced by ω particles and consumption of β matrix due to isothermal martensitic transformation result in reduction of plasticity and increasement of strength.. On the contrary, when the aging time is longer than 4h, disappearance of ω particles and formation of plenty of isothermal martensites are beneficial for the increasement of both strength and plasticity.