The invention discloses a display panel, a manufacturing method thereof, and a display device. The display panel comprises a substrate, a buffer layer formed on the substrate, a semiconductor layer formed on the buffer layer, a gate insulation layer, a gate metal layer formed on the gate insulation layer, and medium layers, wherein the semiconductor layer comprises a source electrode area, a drainelectrode area and a channel area, the channel area is arranged between the source electrode area and the drain electrode area, the gate insulation layer is formed on the position, corresponding to the channel area, of the semiconductor layer, and the buffer layer, the semiconductor layer and the gate metal layer are covered with the medium layers; the medium layers corresponding to the source electrode area and the drain electrode area comprise passing holes correspondingly, the passing holes comprise first passing holes and second passing holes, the first passing holes are connected with the source electrode area or the drain electrode area, the second passing holes are located in the tops of the first passing holes and communicate with the first passing holes, and the hole diameters ofthe second passing holes is greater than that of the first passing holes. According to the display panel, by forming two lap joint holes with different sizes, the gradient of the passing holes is reduced during lap joint of metal wires, and the wires are not prone to breaking.