Provided is a driven axle of an electric rail flaw detection vehicle. A pair of hubs are located at the two ends of an axle case respectively, electric vehicle road wheels are installed on the hubs through hub bolts, two driven axle mounting assemblies are fixedly installed on the portions, close to the hubs on the two sides of the axle case respectively, each driven axle mounting assembly comprises an axle pressing plate, a pressing plate nut, a pair of pressing plate locking screws and an axle support, the axle support is fixed on the axle case, the bottoms of the pressing plate locking screws are fixed on the two sides of the axle support respectively, the axle pressing plate is located on the upper portions of the pressing plate locking screws, one end of the axle pressing plate is screwed on one pressing plate locking screw, and the other end of the axle pressing plate is of a hook structure and is buckled on the other pressing plate locking screw. The invention further discloses an electric rail flaw detection vehicle frame. The driven axle of the electric rail flaw detection vehicle and the electric rail flaw detection vehicle frame have the following advantages that the frame of the rail flaw detection vehicle can be disassembled, data can be effectively collected, and the accuracy of the traveled distance can be guaranteed.