There are many iterative circuit function modules in circuit design.In order to reuse these modules,we proposed an approach which encapsulates circuit function modules into components,and applies these components in the circuit design.Thereby,we accomplished the secondary development on Protel99SE.All the elementary components of the circuit design will be pre-layout through the transforming from SCH to PCB file.The circuit development experiments demonstrate that this kind of circuit platform shorten the circuit development time,reduce the complexity of the circuit design,and improve its effectiveness and the reliability.