The present disclosure provides a method, an apparatus and a system for determining a light-leakage degree of a display panel, and a test fixture, and relates to the field of display technologies. When a light-leakage detection device detected that the plurality of sub-regions includes at least one light-leakage sub-region, the light-leakage detection device can determine a light-leakage degree of the display panel based on an average of brightness values of the plurality of sub-regions and a brightness value of the light-leakage sub-region. Compared with a way that an inspector manually determines a light-leakage degree, the light-leakage detection device can automatically determine the light-leakage degree of the display panel based on brightness values of the sub-regions by the method according to the embodiment of the present disclosure, thereby effectively improving the reliability and accuracy of the light-leakage degree of the display panel as determined.