The multicast technology is applied to the establishment of the realtime radar data sharing network by means of the function of newgeneration weather radar system CINRAD/SC in support of multicast transmission. Based on the existing broadband network, the realtime radar data sharing from citylevel to countylevel could be achieved, which allows county stations to select, except the mode control of radar operation, the functions of the radar system, such as image display and map information setting and resolved the problem of time delay in the previous radar data sharing due to body sweep, data storage, data upload and download. The establishment of the realtime sharing network can help provide guarantee for weather modification operation timely.