A method for residual image test implemented using an apparatus according to claim 7, comprising: playing, using a playing unit, a residual image test picture on a display panel; applying, using an applying unit, a first fixed level signal to each of a plurality of pixel electrodes of the display panel through a data line corresponding to the pixel electrode by turning on all gate lines on the display panel, after playing the residual image test picture on the display panel; and obtaining potential information of the pixel electrode via the data line, using an obtaining unit, wherein the method further comprises, prior to obtaining the potential information of the pixel electrode via the data line: disconnecting, by a gate line control module, the data line from the pixel electrode by turning off all gate lines on the display panel after applying the first fixed level signal, and then applying a second fixed level signal to the data line until a potential level of the data line becomes a second fixed level; floating, by a data line control module, the data line, wherein said obtaining the potential information of the pixel electrode via the data line comprises: connecting, by the gate line control module, the data line with the pixel electrode by turning on all the gate lines, such that the data line outputs a signal corresponding to the potential information of the pixel electrode, and wherein the second fixed level signal is equal to a common voltage signal value applied to a common electrode of the LCD panel, the common electrode and the pixel electrode configured for providing said signals to the LCD panel, and the first fixed level signal is equal to a ground voltage signal value. playing, using a playing unit, a residual image test picture on a display panel; applying, using an applying unit, a first fixed level signal to each of a plurality of pixel electrodes of the display panel through a data line corresponding to the pixel electrode by turning on all gate lines on the display panel, after playing the residual image test picture on the display panel; and obtaining potential information of the pixel electrode via the data line, using an obtaining unit, wherein the method further comprises, prior to obtaining the potential information of the pixel electrode via the data line: disconnecting, by a gate line control module, the data line from the pixel electrode by turning off all gate lines on the display panel after applying the first fixed level signal, and then applying a second fixed level signal to the data line until a potential level of the data line becomes a second fixed level; floating, by a data line control module, the data line, wherein said obtaining the potential information of the pixel electrode via the data line comprises: connecting, by the gate line control module, the data line with the pixel electrode by turning on all the gate lines, such that the data line outputs a signal corresponding to the potential information of the pixel electrode, and wherein the second fixed level signal is equal to a common voltage signal value applied to a common electrode of the LCD panel, the common electrode and the pixel electrode configured for providing said signals to the LCD panel, and the first fixed level signal is equal to a ground voltage signal value. disconnecting, by a gate line control module, the data line from the pixel electrode by turning off all gate lines on the display panel after applying the first fixed level signal, and then applying a second fixed level signal to the data line until a potential level of the data line becomes a second fixed level; floating, by a data line control module, the data line, wherein said obtaining the potential information of the pixel electrode via the data line comprises: connecting, by the gate line control module, the data line with the pixel electrode by turning on all the gate lines, such that the data line outputs a signal corresponding to the potential information of the pixel electrode, and wherein the second fixed level signal is equal to a common voltage signal value applied to a common electrode of the LCD panel, the common electrode and the pixel electrode configured for providing said signals to the LCD panel, and the first fixed level signal is equal to a ground voltage signal value.