The invention provides a pixel circuit, a drive method thereof, an OLED display panel and a display device. The pixel circuit comprises a plurality of row pixel units, a gate drive circuit and a source drive circuit. Each row pixel unit comprises a compensation circuit and a plurality of sub-pixel units. Each sub-pixel unit comprises a sub-pixel drive circuit and an OLED. The input end of each compensation circuit is connected with the source drive circuit through an auxiliary data line. The output end of each compensation circuit is connected with the corresponding sub-pixel drive circuit through a data line and used for generating compensation control signals. The sub-pixel drive circuits are used for controlling the OLEDs to emit light and compensating for the threshold voltage of drive transistors according to the compensation control signals. The extension direction of the data lines is parallel to the direction of laser beams through which the OLED display panel conducts ELA crystallizing. Thus, the design of the pixel circuit is simplified, the opening rate of the pixels is greatly increased, high resolution can be achieved while uniform display is achieved, and cost is reduced while the number of the adopted transistors is decreased.