With the development of industrialization, environmental pollution has become a great challenge for mankind. Acid rain, as a common environmental pollution factor, has caused great damage to agricultural production, human health, building safety and so on. In view of the problems caused by acid rain, a detection system of acid rain pH value based on STC single chip microcomputer is designed in this paper. By detecting the pH value, it can better judge the damage degree of acid rain, and do a good job of prevention as soon as possible. Firstly, the principle of pH measurement is introduced. Then, according to the characteristics of pH measuring electrode, the design of acid rain measurement amplifying and conditioning circuit is designed. Because the temperature is the important factor that affects the accuracy of pH value, the temperature compensation circuit is designed by using the temperature sensor. Finally, through the GPRS wireless transmission system, the collected acid rain signal value is sent to the PC. The experimental results show that the data collected by the measurement system can meet the requirements of the system design. Each module has normal function and the software program control is in line with the design requirements. The acid rain measurement in the experiment is verified by a standard pH meter, with a deviation of between 0.04pH. The system has the characteristics of low cost, small size, low power consumption and high accuracy. After testing, the acid rain detection system has higher pH value measurement accuracy and temperature measurement accuracy, and the measuring end can accurately measure data and send it reliably and stably to the data management platform of PC.