According to the relationship among pressure, temperature and altitude, a digital barometer with MS5534C digital pressure sensor based on MEMS of Intersema company was designed. Use I/O control of single chip P89LPC936 to realize P89LPC936 to receive air pressure data from digital pressure measuring module MS5534C, transfer data to current altimeter by software processing, and display altimeter on LED displayer in real time. The barometer prototype has advantages of light weight, low power cost, high precision. The barometer was tested in the standard atmospheric condition, which has a relative altitude average standard deviation of 3 m.