The invention, which belongs to the technical field of the power, especially relates to a wind power plant energy storage testing system and evaluation method. According to the invention, an outgoing line is arranged at the main transformation high-voltage side of the wind power plant and a bus is arranged at the low-voltage side; and incoming lines of all fan current collection circuits, a wind power plant passive compensation device, and an energy storage device. With the system and the method, the performance of the energy storage device can be effectively detected and the improvement effect of the wind power plant stability can be verified. Moreover, the workload is simplified; the operation is simple, flexible, and convenient; the processing capability is high; the data processing becomes flexible; the testing method is simple and practical; the collected data quantity is small; and the capability of image outputting is realized. In addition, a favorable external data interface can be provided; and the testing result analysis can provide comprehensive evaluation for the performance of the energy storage device. Therefore, the provided system and method are suitable for the performance testing analysis of the energy storage device arranged at the wind power plant.