With the rapid development of computer software and hardware, virtual instrument technology pushes the development of measurement and control instruments to a new height. The virtual instrument development mode takes the computer hardware as the carrier and the software as the soul, which is widely used in the scientific research and production of electronics, communication and other fields. The paper introduces the design of MLS receiver precision test system based on Lab Windows/CVI platform and the concept of virtual instrument. The paper first gives the definition and theoretical calculation method of MLS receiver precision, then discusses the overall design as well as software and hardware design scheme of the precision test system, finally summarizes and prospects the design of the test system.