In order to meet the needs of city atmospheric concentration monitoring

an intelligent city atmospheric sensor system is developed based on wireless sensor networks（WSNs）

using electrolytic gas sensor.The hardware and the software design of the system are introduced

and test results are given.There are many functions in this system

such as monitoring

display

alarming and communication

and using WSNs

this system overcomes limitation of wired sensor networks and avoids shortcomings of high power consumption of other wireless communication technologies.Experiments show that the system has characteristics of real-time

high reliability and low power consumption

it effectively realizes real-time detection and monitoring on harmful gases in atmosphere of city.