Abstract: With the rapid development and widespread application of computer technology, especially microelectronics technology, many traditional machinery and electronic equipment have new progress and new function by combining with software technology. This paper discusses the development progress of measuring device and expounds the measuring principle, design concept, measuring process of GPS/BDS intelligent software length measuring device, and proposes the method of calculating integer ambiguity by combining pseudo-range and carrier phase. It is verified by experiment that software length measuring device has the characteristics of non-contact measuring, direct range measuring and millimeter measure precision. It can be exploited for intelligent, automated, miniaturized, modularized and open system devices, so it has broad market and application prospect.