Abstract: Aim To introduce a method for vehicle auto classification based on the loop sensors, which can check the frequency change caused by the vehicle ferromagnet. Methods The fuzzy pattern recognition with character separation was used to classify vehicles accoding to the curve from the loop sensor since there is a set of characters which can uniquely describe a kind of curve. Results The method and related equipment were applied in the road and bridge toll system and the traffic flow statistics system. Conclusion The fuzzy pattern recognition method proposed can classify vehicle property accurately.