Abstract: A methodology based on the feature curve of deformation is used to perform the integral body modal analysis.By this methodology the first global bending and the first global twisting mode of a coach body can be easily and quickly identified from the complicated local mode,and the extraction of the global mode is less depending on experience but more objective.A modal analysis of an integral bus is carried out.Fitting the global deformation characteristic curve of the bus by the use of statistical method,the first global bending and the first global twisting mode can be easily extracted,which verify the validity of the method.