Compared with developed countries, food safety problems in China are more severe. How to improve the food safety level and reduce the frequency of food safety incidents under the existing conditions of science and technology? This is not only the subject of security research, but also the subject of science and technology management and application. By theoretical researching, a multidimensional food safety supervision system is constructed. At the same time, eight principles of food safety supervision are put forward. In this system, supervision in advance, supervision in process and supervision afterwards are used. After doing this, research of early warning and positioning of food safety is finished. On this basis, we take two HOPSCAs at a China's west city as examples. After two years of researching, the analysis of early warning and positioning is all finished. Based on the results of early warning and positioning, the management level of food safety for these HOSPCAs is effectively improved. Finally, six specific countermeasures for food safety supervision are put forward based on the scientific and technological progress.