The present invention relates to the mass concrete construction technology field, especially to a mass concrete water temperature automatic control method and device. The method comprises: responding the user's operation to set the cooling water temperature passing through mass concrete in a first period, responding the user's operation to set the target water temperature passing through the mass concrete in a second period, controlling the part of a water pipe to flow out water flow with the first preset temperature of a first preset flow, and controlling the other part of the water pipe to flow out water flow with the second preset temperature of a second preset flow to allow the temperature after mixing the water flow of the first preset temperature of the first preset flow and the second preset temperature of the second preset flow to be the cooling water temperature or the target water temperature so as to perform automatic control of water temperatures in the first period and the second period.