The invention discloses a display panel and a detection method thereof, a flexible circuit board and a display device. A second binding area in the flexible circuit board comprises a plurality of contact pads and at least one test pad group, wherein the plurality of contact pads are used for being bound to a plurality of corresponding contact electrodes in a first binding area; each test pad groupis used for being bound to a corresponding test electrode group in the first binding area and comprises a plurality of test pads; the test pads are used for being bound to corresponding test electrodes; and the test pad groups are also used for judging the binding state of the plurality of contact pads and the plurality of contact electrodes through detecting the on-off states between the test pads and the corresponding test electrodes after the first binding area is bound to the second binding area. According to the flexible circuit board disclosed by the embodiment of the invention, the binding effect can be effectively and quickly detected through arranging the test pad groups in the second binding area and binding the flexible circuit board and the display panel.