Molecular dynamics (MD) simulations were conducted to investigate the influence of temperature on primary radiation damage in tungsten (W). By investigating on the number of surviving defects, it was suggested that the increment of temperature improved the radiation resistance of the W, which was further improved with the existence of grain boundaries (GBs). Second, the maximum average kinetic energy of all of the atoms in the GB comprehensively reflected the influences of the temperature, the primary knock-on atom (PKA) energy, and the distance between the PKA and GB on the overlap of the cascade center and the GB. Thus, it could be regarded as a quantitative factor that explained the GB influence on the evolution of the interstitials. Finally, the size distribution of the interstitial clusters exhibited negative correlation with the temperature. In contrast, when the temperature rose above 900 K, the size of the vacancy cluster increased with temperature.