Vehicle’s sliding resistance mainly includes rolling resistance, air drag resistance and friction within the transmission, wheel bearings and other related components. Among those, rolling resistance and air drag always exist whenever vehicle is running, so they have great influence on vehicle’s dynamic performance and fuel economy. Therefore, it is important to determine vehicle’s rolling resistance coefficient and air drag coefficient quickly and accurately in order to operate vehicle properly and reduce the vehicle’s fuel consumption. Combining theoretical analysis with experimental verification, calculation model based on road coasting test was given by means of least squares principle. And through which vehicle rolling resistance coefficient and air drag coefficient were determined easily. Then by using the test data from some Minibus, the vehicle's rolling resistance coefficient and air drag coefficient are calculated according to established model. The computation result shows that rolling resistance coefficient is a linear function of the speed and the air drag coefficient is constant. Finally, the analysis shows that the calculation model is simple, precise and useful.