The invention provides a test method of reactive power compensation device response time. A reactive power compensation device is connected to a low voltage side bus of a wind power plant boosting transformer through a power grid voltage generator. The test method comprises the following steps of testing reactive power investment response time of the reactive power compensation device and testing reactive power quit response time of the reactive power compensation device. In the method, the power grid voltage generator generates power grid voltage drop and recovery on a reactive power compensation device machine end so as to trigger reactive power investment and quit of the reactive power compensation device. An operation condition of the reactive power compensation device during testing is consistent with the operation condition during normal operation so that response time obtained through testing is guaranteed to completely cover a whole response process of the device. A test result is consistent with a result during actual operation so that confidence of the test result is high. Good versatility is possessed. The test method is suitable for all kinds of the reactive power compensation devices and is not influenced by a device function and performance. Test result accuracy is high.