In today's society,the problem of water pollution is getting more and more serious.In order to conduct timely and effective detection of urban water pollution and ensure people's healthy water use,it is necessary to use analytical instruments such as atomic absorption spectrophotometer to detect water quality.Based on the traditional photometer instrument,an online atomic absorption spectrophotometer based on the cloud technology of the Internet of Things was designed,and the cloud communication system of the photometer was designed in detail.The system is composed of cloud server and front-end and back-end software programs.The overall architecture of the system is designed using Python language.The MQTT IoT communication protocol and WebSocket protocol are used to realize remote communication of data and instructions from cloud servers,mobile clients and field working instruments.The actual test results show that this system achieves the function of real-time two-way transmission of information,and it has better completed the online water quality detection of the instrument.The design of this system has also improved the work efficiency of environmental monitoring personnel,and enabling water quality environmental monitoring to embark on a scientific and intelligent development path.