The invention provides an internet of things based public food sanitation safety protection service system and a working method thereof. The system comprises a wireless sensing node, a network gateway and terminal equipment, wherein the wireless sensing node is connected with the network gateway by wireless; the network gateway is connected with the terminal equipment through the Ethernet and a wireless local area network; system software is installed on the wireless sensing node and the network gateway respectively; and terminal software is installed on the terminal equipment. Under the control of the system program, acquisition, processing, transmission, analysis, monitoring, feedback, information exchange and service customization on temperature, humidity, cleaning disinfection, pesticide residue index, nutrition tracing, additive dosage and other related data can be realized, and an intelligent monitoring platform for municipal supervision department, homology of medicine and food service platform and a humanistic concern and business information service platform can be formed.