Aiming at the fact that the Michelson′s interferometer needs artificial counting the interference rings, a kind of interference ring autocount device is designed. The optoelectronic sensor and thresholds comparator are used in the device to collect the interference ring, producing the electric impulses corresponding to the light and dark fringes. The electric impulses are counted and displayed by the microcontrollers. In order to eliminate the interfering impulses generated by circuit noise, the delay technology of is used in the software, which improves accuracy of pulse counting. The experimental result shows that the device is accurate and feasible for Michelson interference experiment.