本文根据气体状态方程．推导了二元混合气体浓度（成份）与声速的解析关系，得到一个一元二次方程，该方程的系数是声速与温度的函数，而方程的解即为气体浓度。研制了带单片机的智能超声氯气浓度分析仪，根据测量的声这与温度进行直接运算而无需现场实测一一逐点标定，该机的计算误差小于１％，经工厂使用并与化学分析对比，其概然误差小于０．１％。 This article based on the gas equation of state. The analytic relation between the concentration of binary mixed gas and the velocity of sound is deduced and a quadratic equation is obtained. The coefficient of the equation is a function of the velocity of sound and the temperature, and the solution of the equation is the gas concentration. A smart ultrasonic chlorine concentration analyzer with a singlechip was developed. According to the measured sound and the temperature, direct calculation without the need of field measurement one by one calibration, the calculation error of the aircraft is less than 1%, by the factory and compared with the chemical analysis, The overall error is less than 0.1%.