The invention relates to a test device and a test method of running of a yaw system for a wind turbine generator system. The device comprises a control system and a yaw system, wherein the yaw system comprises a yaw bearing, a rack, a yaw motor, a yaw transmission, a lubricating device, a yaw brake disc, a pair of yaw brake calipers and a hydraulic station, and the control system comprises a PLC (Programmable Logic Controller) and a data collector; the yaw motor, the electronic brake, the hydraulic station, the lubricating device and the data collector are respectively and electrically connected with the PLC. The test device and the test method provided by the invention have the advantages of reasonable design, convenient use and simple operation, the whole process of running of the yaw system for the wind turbine generator system can be fully tested, and whether the performance of the yaw system meets the on-site operation requirements or not can be fully detected in the factory.