Objective To investigate the effect of contrast agent temperature on adverse reactions of transvaginal four?dimensional hysterosalpingo?contrast sonography （TVS 4D?Hycosy） with pain as the main manifestation. Methods Double?blind randomized controlled study. A total of 220 patients who underwent TVS 4D?Hycosy examination were randomly assigned （1∶1） to receive preheated contrast agent （38 ℃） and normal temperature contrast agent （22 ~ 26 ℃） respectively. The Stacey scoring scale was used to comprehensively evaluate pain， nausea， vomiting and other adverse reactions and NRS scoring scale were used to evaluate pain alone， and the occurrence of adverse reactions after intrauterine catheterization and during the examination was compared between the two groups. After the inspection， compare the proportion of people with persistent pain at 0 h， < 0.5 h， < 1 h， 1 ~ 24 h， and > 24 h between the two groups. Result There was no significant difference in Stacey adverse reaction score and NRS pain score between the two groups after intrauterine catheterization （Z = 0.231， -0.341， both P > 0.05）. During the examination， the Stacey adverse reaction score and NRS pain score in the preheated group were lower than those in the room temperature group （Z = 2.906， 3.837， both P < 0.05）， and the proportion of moderate and severe adverse reactions in the preheated group was lower than that in the room temperature group （χ² = 7.502， P < 0.05）， the difference between the two groups was statistically significant. After the examination， there was no significant difference in the proportion of people with persistent pain at 0 h， < 0.5 h， < 1 h， 1 ~ 24 h， and > 24 h between the two groups （χ² = 0.141， 0.566， 0.697， 0.373， all P > 0.05）. Conclusions Thermostatic preheated contrast agent reduces adverse reactions during the TVS 4D?Hycosy and is a simple and effective way to alleviate patient suffering.