The invention provides a power transformer oil surface temperature meter comprising a casing, a main control circuit board and a display circuit board, wherein the main control circuit board and the display circuit board are arranged in the casing. The main control circuit board is provided with a controller and an RS485 conversion circuit, wherein the controller is used to calculate the deviationof the transformer oil surface temperatures collected by two random digital temperature sensors, the transformer oil surface temperatures collected by two digital temperature sensors with the minimumdeviation are selected, and the average value thereof is calculated and serves as a current transformer oil surface temperature; and the RS485 conversion circuit is electrically connected with the controller and used to forwarding the current transformer oil surface temperature sent by the controller to an external system. The display circuit board is provided with a displayer used to display thecurrent transformer oil surface temperature sent by the controller. The power transformer oil surface temperature meter integrates transformer top layer oil temperature measurement, on-site display and data communication and has the advantages of being simple in structure, simple to install and capable of performing data communication with a computer system.