Abstract: A non-contact height measuring instrument using infra-red sensing technology is designed． This system takes SCM ( Single Chip Microcomputer) as controller，designs the infra-red transmitting and receiving circuit，at the same time uses the motor and its drive to cooperate with the infra-red for measuring height and completes corresponding software program． The experimental results show that the instrument has simple facilities and easy to realize． It also has the high accuracy and reliability and can be intelligent applied to non-contact height measurement．

Key words: infra-red technology, height measurement, motor of Bujin, single chip microcomputer(SCM)