In recent years, there are many frauds found in the enterprises, it causes the bankruptcies of businesses. Therefore, how to utilize multi-layer responsibility structure to ensure the achievement of goals has become an important issue for the enterprises. Accordingly, constructing internal control process conformed to the objective of the organization and building a standard internal auditing mechanism is an important part of the internal control for an enterprise. Due to the internal control and auditing system of the case study company are not complete, the control processes need to be improved and institutionalized. Moreover, the control process of the billing demand management for the company still retains part of manual operations, for example, writing an application form, an audit report, registration and archiving in manual operations without a standard management model, and therefore it leads the processes are more difficult to trace. In this research, billing demand management is used as an example. In addition, Organizational Process Focus process area of the Capability Maturity Model Integration (CMMI) is applied to the case study, and the IDEAL model is employed to help establish the process mechanism of internal control. Also, this process mechanism can be improved continuously. With the adoption of CMMI, it can enhance and standardize the internal control and auditing process of the organization.
