Firstly, this paper introduces current situations of protection of capital farmland. According to current situations, it analyzes significance in protecting capital farmland and significance and functions of application of 3S technology in dynamic monitoring of capital farmland. With the aid of examples, it discusses functions of remote sensing and GIS in dynamic monitoring of capital farmland. It is believed that 3S technology not only can provide accurate parcel data of capital farmland changes for reviewing land change survey, but also can provide data for monitoring development situations of capital farmland, as well as provide basic current information for decision-making department.