To determine the effect of temperature and microstructure on the fatigue crack propagation behavior in Ti-3Al-2.5V alloy, experimental investigations have been carried out with the specimens of different temperatures and different volume fractions of prime $alpha$-phase. The temperatures employed were room temperature, 20$0^{circ}C$, 30$0^{circ}C$ and 40$0^{circ}C$ under the same frequency of 20Hz. To obtain the different volume fractions of the primary $alpha$-phase, specimens were solution-treated at $alpha$+$eta$ and above the $eta$ region. From the experimental results, following conclusions were obtained. (1) ΔKth was observed to increase with the less volume fraction of the primary $alpha$-phase. (2) As the temperature increased. (3) Microstructures having more primary $alpha$-phase showed higher strength at the high temperatures.