The invention relates to a pixel circuit, a control method thereof, a display panel and a display device. The pixel circuit includes a transistor T1, a transistor T2, a transistor T3, a transistor T4,a transistor T5, a transistor T6, a transistor T7, a transistor T8, a transistor T9, a capacitor C1, and a light emitting diode D1. The pixel circuit uses a second reference voltage Vref2 to compensate a control terminal of the transistor T1 through the capacitor C1 so as to make a driving current flowing through the transistor T1 is related to the second reference voltage Vref2 and independent of first power supply VDD. Since the driving current flows through a power supply line, when the driving current is independent of first power supply VDD, current-resistance voltage drop on the power supply line has no effect on the driving current, thereby improving the illumination uniformity of a screen.