Abstract: To investigate the method to obtain the real-time longitudinal acceleration based on its velocity, vehicle acceleration is obtained through the velocity filtering, differential, and then filtering. Power spectrum analysis of velocity and acceleration is discussed and its Fir lowpass digital filters are designed with Fdatool box in the Matlab development environment. A kind of algorithm fitted for real-time use by a vehicle is developed and its application in microcomputer is discussed. The experimental results revealed that the algorithm is of good real-time and high precision.