The invention discloses a test method and a test system for cut-in voltage. The test method and the test system for the cut-in voltage comprise coarse scanning of the cut-in voltage and accurate scanning of the cut-in voltage, wherein through the coarse scanning, a grid terminal voltage value, namely the cut-in voltage, generated when a drain terminal current is greater than a target current for the first time can be quickly determined; through the accurate scanning, a scanning step length is shortened continuously until the scanning step length is shorter than a set step length; and every time the scanning step length is shortened, on the basis of the cut-in voltage determined in the former time, the scanning is conducted according to the current shortened scanning step length, and then the cut-in voltage under the condition of the current shortened scanning step length is determined again. According to the technical scheme of the test method and the test system for the cut-in voltage, high resolution and high precision test conversion is added into a second scanning test to automatically increase or decrease the scanning voltage, and therefore the testing of the cut-in voltage is enabled to be more efficient and more accurate.