Abstract: Temperature is one of the most important parameter to be controlled in almost all industrial plant, since it directly affects on product quality. The main objective of this paper is to study and construct 8051 based temperature control system. In this control system AT89S51 microcontroller is used. To sense the temperature, IC temperature sensor, LM 35DZ is used and its sensing range is up to 150°C. This paper aims to apply for heating process in traditional medicine production. The required temperature of heating process is under 110°C. When the temperature is greater than the required temperature, the product quality will be low and if the temperature is less than power and time consumption will be large. So this process requires temperature regulation. LM 35 is precision integrated-circuit temperature sensor, whose output voltage is linearly proportional to the Celsius temperature. Its accuracy, low cost and temperature range are desirable for this heating process.