The utility model relates to the electric equipment condition monitoring field, in particular relates to a power transformer assessment system. The power transformer assessment system disclosed by the utility model includes a data acquisition device, a data receiver, a data converter and an upper computer, wherein the data acquisition device arranged on a power transformer acquires environment temperature values and current values of the power transformer and transmits the environment temperature values and the current values to the data receiver, the data receiver transmits the environment temperature values and the current values to the data converter, the data converter converts the environment temperature values and the current values into data in preset formats, and transmits the converted data to the upper computer, and the upper computer obtains corresponding capacity-increase assessment opinions according to the received data. Based on the acquisition of the environment temperature values and the current values of the power transformer, the power transformer assessment system can assess the capacity-increase ability allowed by the power transformer system, and therefore, the stable operation of the power transformer can be ensured.