The invention belongs to the technical field of machining measurement, and in particular relates to a step depth measurement tool, which includes a measurement base, a first support, a second support, a measurement plate, a measurement head, a displacement sensor, a signal conditioner and a computer. The first support and The measurement base is slidingly connected, the second bracket is slidingly connected with the first bracket, the sliding direction of the second bracket is perpendicular to the sliding direction of the first bracket, one end of the measuring board is slidingly connected with the second bracket, and the sliding direction of the measuring board is perpendicular to the sliding direction of the first bracket. The sliding directions of the two brackets are perpendicular to each other, the measuring head is slidingly set at the other end of the measuring plate, the sliding direction of the measuring head is the same as that of the second bracket, and the measuring head slides close to or away from the measuring base, and the displacement sensor is fixedly arranged on the measuring base On the head; the signal conditioner is used to receive the signal transmitted by the displacement sensor, and to amplify and filter the signal, and the signal conditioner is electrically connected to the computer through the data processor.