The invention discloses a motor axial gap and axial extension dimension detection device. The device comprises a bottom board, an indicating gauge, and a bearing seat A, a bearing seat B and a bearing seat C which are mounted on the bottom board, wherein the indicating gauge is respectively provided with a pad, a precise spring and a flat gauge, the indicating gauge is mounted on the bearing seat A, the precise spring is arranged between the pad and the flat gauge, a standard block is arranged below the flat gauge, a linear force measurement gauge is arranged below the bearing seat C, the linear force measurement gauge is connected with a sliding block through a switching sleeve, and the lower end of the sliding block is connected with a connection rod. Through the detection device, high precision and no damage to axial extension are not only realized, but also measurement on an axial gap and axial extension dimensions can be realized through one measurement, measurement precision is accurate and reliable, operation efficiency is high, product quality is guaranteed, great importance to production demands is realized, and the detection device can be widely popularized and applied to the motor axial gap and axial extension dimension detection field.