In order to ensure the safety of internet of things for smart city and ensure normal operation of smart city, the network security situation of internet of things should be monitored correctly for a long time, therefore the fuzzy neutral network with wavelet package and chaos particle swarm algorithm are applied to monitor the network security situation. Firstly, the basic theory of network security situation of internet of things for smart city is analysed, the corresponding mathematical is constructed, and the security situation awareness framework of internet of things is designed. Secondly, the basic theory of fuzzy neutral network is studied, and the structure of the fuzzy neutral network is designed. Thirdly, the processing method of network security situation data based on wavelet package is constructed. And then training procedure of fuzzy neutral network based on chaos particle swarm algorithm is established, the algorithm procedure is designed. Finally, the simulation analysis is carried out using a smart city as example, and the network security situation of internet of things for it is monitored correctly, then the network safety can be ensured.