In this work, the cavitation conditions at high temperatures and pressures in acetone containing deuterium were numerically estimated based on multifunction cavitation in conjunction with large microjets. The predicted bubble shrinkage velocity of 1.114 × 103 km/s satisfies the requirement for bubble fusion, which requires a shrinkage velocity greater than 1.00 × 103 km/s. The internal pressure and temperature of a bubble were found to drastically increase to 7.26 × 108 bar and 6.8 × 108°C, respectively, as the bubble radius shrinks from 100 to 0.1 μm. This temperature is sufficient for bubble fusion, which requires a temperature above 1.0 × 108°C. These results suggest that multifunction cavitation may be capable of generating bubble fusion.