How to use the existing and rich continuous operation reference stations (CORS) resources to provide high precision, high reliability, and high concurrency differential augmentation signals for precision agriculture is still an unsolved problem. Based on the characteristics of agricultural application, a CORS and UHF radio GNSS based differential signal relay scheme was proposed, which can solve the problems such as single transmission mode, lack of concurrency, high cost of using in CORS application, repeated construction, frequency interference and frequency interference existing in single RTK station application. An experimental CORS system with three stations was established. The stations were established in Haidian District, Shunyi District and Pinggu District of Beijing. Three sets of relay test systems based on PC, i80, and Phone were constructed. The positioning performance verification, operation unit control accuracy verification and application prototype verification were carried out respectively. The test result showed that within 10km, the plane inside and outside accuracy values of relay positioning were better than 0.022m and 0.033m, which met the requirements of agricultural machinery operation (usually 0.03m). The control accuracy of the operation unit reached 0.066 ~0.076m, slightly higher than 0.050m. The reliability of the phone based relay system was high, and the system had good expansion. Therefore, by using smart phone and UHF radio, the differential signal of CORS can be easily obtained and transmitted, which can realize RTK positioning by the rover within 10km.The mode was easy, low cost, and had certain feasibility and application value.