Abstract: Some experimental α+α₂ alloys were prepared by the addition of tin or aluminum elements into Ti-55 alloy. These alloys were designed with varied electron concentration values and named as Sn-rich alloys and Al-rich alloys, respectively. The precipitation and growth of α₂ ordered phase in the tested alloys under various heat treatment conditions were investigated. Some comparisons among the experimental results were performed and discussed in detail. Stronger precipitation and growth of α₂ ordered phase were caused in Al-rich alloys but relatively weak change in Sn-rich alloys with increasing the electron concentration. The precipitation of α₂ ordered phase in Al-rich alloys is stronger than that in Sn-rich alloys when the electron concentration value is the same for the two alloys.