Abstract: A method for measuring kink effect of a first semiconductor device including the following steps is disclosed herein. Firstly, choose a second and a third semiconductor device. The first, the second and the third semiconductor device have the same channel length and different channel width. The next step, apply a voltage on the drain electrode of respective semiconductor device. The voltage is applied to the drain electrode and the DIBL effect is avoided. The following step, measure the threshold voltage of every. Next, measure the source to drain current by applying the respective threshold voltages on the respective gate electrode of every semiconductor device. Subsequently, generates a slope by dividing a first drain current difference by a first channel width difference. The first drain current difference is formed of subtracting a second drain to source current of the second semiconductor devices by and a third drain to source current of the third semiconductor device.