The expert system application are developed in line with the existence of information technology. The development of expert systems aims to be a means of assistance to provide solutions in our lives. This expert system can help technicians get solutions quickly and can save time. Expert systems use computer technology to integrate, manipulate and display information or characteristics. Expert systems can also help in making better solutions. With the very rapid technological advances today, an idea or idea has emerged from the author to try to implement one of the expert system application programs into the quality of service activities of computer technicians. The author tries to build an application that will help to facilitate the provision of solutions to computer damage to hardware so that it can make it easier for users or technicians to get solutions quickly. The system to be created is "Designing an Expert System for Diagnosing Computer Problems Using Visual Basic" This system will use the prototype method and tools for modeling using UML (Unified Modeling Language). This system is built using the Visual Basic 6.0 application to process the Microsoft Access database.