The effect of holding time of double annealing process on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-1Cr-1Fe (Ti55511) alloy was investigated.Results reveal that the shape and size of the primary α (α_p) phase are predominantly influenced by the holding time at the first stage. With the prolongation of holding time, the long strip of α_p is transformed into a short rod due to the terminal migration mechanism, leading to the broadening growth, and the growth of α_p slows down when the holding time is over 2 h. The volume fraction of α_p is mainly affected by the holding time of the second stage: with the prolongation of holding time, the volume fraction of α_p is increased, which is accompanied by the precipitation of the secondary α (α_s). The mechanical properties of Ti55511 alloy are influenced by both α_p and α_s. Tensile results indicate that the optimal holding time of double annealing is 1–4 h for the first stage and 0.5–2 h for the second stage.