本文提出运用过路车来测出既有钢筋混凝土桥梁动态参数 ,利用所得振型评定桥梁承载能力。该方法可以实现在线评定 ,简便易行且有很好的精度 ,利用该方法评定桥梁可以节约大量经费 ,为既有桥梁的加固提供可靠数据。 This paper proposes to use the passing car to measure the dynamic parameters of the existing reinforced concrete bridges and to use the obtained vibration modes to evaluate the bearing capacity of the bridge. The method can be used for on-line assessment, which is simple and easy to operate with good precision. Using this method to evaluate bridges can save a lot of money and provide reliable data for the reinforcement of existing bridges.