The growth behavior of β grains in a TB18 titanium alloy during heat treatment and its impact on hardness were investigated. The results indicate that when subjected to isothermal heating at 840~990 ℃,the isothermal growth curve of β grains in the TB18 titanium alloy follows an exponential relationship, with a β grain growth index (n) ranging from 0.12 to 0.16. Dynamic factors play a dominant role in β grain growth, although their influence diminishes with prolonged holding time. The activation energy for β grain growth of the TB18 titanium alloy ranges from 49.53 to 56.68 kJ/mol. The increase in the hardness of the TB18 alloy is attributed primarily to the increase in lattice distortion resulting from complete atom dissolution and the promotion of ω-phase precipitation.