The utility model discloses rain -proof cover of transformer thermometer belongs to transformer auxiliary assembly technical field, including casing, preforming, observation window, glass board. The utility model discloses a size is proper with transformer thermometer collocation, can effectively prevent to take place because of the phenomenon that the casing rocked the glass shell of smashing the thermometer. The size of preforming is lighter than the construction bolt interval of thermometer, can make things convenient for and between the construction bolt that inserts the thermometer fast block the thermometer, can play the effect that prevents rain -proof cover and come off when rain -proof cover installation puts in place playing. The utility model discloses have all -round rainproof function, lowering the temperature shows the spoilage, improves substation equipment's operational reliability. The utility model discloses the cost of manufacture is moderate, and tensile strength is stronger, and hardness is high, and is stand wear and tear, does benefit to long -term use, especially is fit for the weather in northeast. Use the utility model discloses intensity of labour that can the greatly reduced installer improves work efficiency, and save time cost and human cost have fabulous economic value.