Relationship management is the key to the success of a modern firm．As a new method to process the nonlinear data‚the Kernel method provides a feasible scheme to analyze the complex relationship networks in firms．In this paper‚based on the analysis of the core concepts in the Kernel method‚the basic principles of the multiclass classification based on the one-class classification were studied‚and the reliability function applied to the multiclass classification was put forward‚which makes the classification results more reliable．Finally‚the method was applied to the data analysis of the relationships between a firm and its suppliers．The results reveal the validity of the proposed classification method．