The embodiment of the invention discloses a system and method for improving reliability of a component software system. The system comprises a source code component generating subsystem, a component managing subsystem, a component assembling subsystem and a reliability evaluating device. The source code component generating subsystem is used for generating frame components and code components, wherein the frame components and the code components meet standards. The component managing subsystem is used for carrying out retrieval, deleting and running management on the components through a component managing information base in an information managing tool. The component assembling subsystem is used for providing component query conditions and downloading needed components from a component base to local for use through a querying and downloading interface provided by the component managing subsystem. The reliability evaluating device evaluates the reliability of application software generated by the components and detecting whether the quality of the software meets demands or not. Reliability influencing factors of the whole component software system are mapped to all the components, and the feedback of the reliability evaluating device is used for improving the reliability of the component software system.