The β grain growth behavior of a novel high strength TB18 titanium alloy was investigated through the variation of β grain size in TB18 titanium alloy under the conditions of different temperatures and holding times. Results show that the heat treatment temperature and holding time have significant effects on the β grain growth of TB18 titanium alloys. The β grain size is increased with increasing the solution temperature and holding time. Besides, the coarsening temperature of TB18 alloys is 920 °C. The grain growth exponents and grain growth activation energy were calculated by Beck equation and Arrhenius equation, respectively. The grain growth exponent n is 0.13~0.26 for the TB18 alloys. The grain growth activation energy of the TB18 alloy is 34.27~60.58 kJ/mol.