A liquid crystal display and a method for testing the liquid crystal display are disclosed. The liquid crystal display includes a TFT substrate including M scan lines and N data lines, a drive power line, and a switch unit adapted to connect the drive power line to the M scan lines under control of a control signal during a detection of a source of Mura of the liquid crystal display. The testing method includes: applying the control signal to the switch unit; applying a data signal to the N data lines; determining the source of the Mura of the liquid crystal display according to a current brightness of the liquid crystal display; and stopping applying the control signal to the switch unit.