The invention belonging to the technical field of displaying discloses a pixel circuit and a driving method thereof, a display panel and a display device. The pixel circuit comprises a driving transistor with a double-gate structure, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first capacitor, a second capacitor and a light-emitting device. All the transistors and the capacitors cooperate with each other to compensate a threshold voltage of the driving transistor, so that the driving current for driving the light-emitting device to emit light is only associated with a voltage of a data signal and thus the influence on the light-emitting device by the threshold of a driving control module is eliminated. When different pixel units are loaded by using a same data signal, images with the same brightness are obtained, so that uniformity of image brightness of a display region of a display device is improved and the difficulty of gamma voltage adjusting by the pixel circuit is reduced. Moreover, the selection range of the data signal is further optimized, so that energy consumption is reduced.