Due to the frequent occurrence of building fires, the mechanical properties of concrete, as the most widely used construction material, are severely challenged under high temperatures. To explore the effect of granite manufactured sand content on the performance of ultra-high performance concrete (UHPC) after heating and cooling treatment, three types of UHPC specimens with different manufactured sand contents (0, 50%, and 100%) were prepared in this study. Then, the effects of manufactured sand content, heating temperature, and cooling regime on the P-wave velocity and uniaxial compressive strength of UHPC were obtained through experiments. The results indicate that the P-wave velocity and compressive strength of UHPC both increase slightly with the increase in manufactured sand content. When the specimen is heated from a room temperature of 25 ℃ to 300 ℃, the corresponding P-wave velocity and compressive strength decline gently. When the target temperature is raised to 600 ℃ and 900 ℃, the corresponding P-wave velocity and compressive strength decrease sharply. In addition, it is revealed by the investigation of cooling regimes that the decrease in P-wave velocity and compressive strength of the specimens under water cooling is greater than that under natural cooling, indicating that secondary damage to the specimens is caused by the thermal shock induced by water cooling.