In order to overcome the deficiency of traditional network RTK (real-time kinematic) positioning, a center differential positioning system, cenDPS, was proposed based on the internet. This system is on the basis of the traditional network RTK technology and centers the differential processing on the cenDPS server to greatly reduce the requirement for the rover receiver. This concentrated cenDPS can monitor rover's high-precision location in real-time and is an important aspect for the research and development of location-based service. The availability of the cenDPS was checked by a test. The test results show that average initialization time for the system is about 73 s, and position resolution with centimeter-level accuracy can be obtained in real-time.