The effects of different cooling rates on the microstructure evolution and tensile properties of TB17 titanium alloy were studied. The results show that the cooling rate has a significant effect on the microstructure. When the cooling rate is low, the alloying elements are diffused fully, resulting in higher content and larger size of coarse lamellar layers, and a small amount of secondary α phase is precipitated in the matrix. When the cooling rate is high, a large amount of microstructure at high temperature is preserved, so that the coarse lamellar content is low and the size is small, and the secondary α phase is hardly observed. Due to the absence of external forces, the lamellar α phase maintains a strict Burgers orientation correspondence with the β phase. The tensile property is greatly affected by the solution cooling rate. A large amount of secondary α phase is precipitated during air-cooling (AC), which results in the highest strength. Due to the faster cooling speed, only the coarse layer is retained during water-quenching (WQ), resulting in the lowest strength. The cooling rate of furnace-cooled (FC) is too slow, so the coarse lamellar growth is obvious. This inhibits the precipitation of secondary α phase, and leads to the middle intensity. After aging treatment, the tensile properties change differently. WQ has the highest strength, while FC has the lowest strength.