With the popularity of greenhouse technology, the amount of greenhouse is larger and lager. However, the temperature control of greenhouse is becoming a difficult problem. Currently,the temperature control system of greenhouse is mostly using a transfers system which consists of analog temperature sensor, multiplexing analog switches, AD conversion units and SCM. This kind of temperature collection system needs a lot of cables which is laid to make the single of the sensor be sent to the collection card in the greenhouse.Thus the work of fixing and take-down is miscellaneous,and the cost is high.What’s more,the transmission line is analog signal which are vulnerable to interference and loss, measurement error is relatively large, were not conducive to control temperature in a timely manner according to a decision. In this form, to develop a real-time, high precision, integrated approach to multi-point temperature measurement and control information system will be necessary. This issue gives a temperature control of greenhouse based on SCM and digital monobus technology. In this project,the change of temperature in the greenhouse is transformed into the change of electric current and then into the change of voltage by using the temperature sensors.The change of voltage is input inio the AD conversion units and the result is dealt with by SCM.At last the realtime temperature in the greenhouse is displayed on the monitor under the control of SCM.Once the value of the temperature in the greenhouse exceeds the minimum and maximum whieh is preestablished.SCM will start the control device, and thus to control the temperature inside the greenhouse. To be able to the multi-channel data acquisition and processing ,system is a mian machine and a number of lower machines structure. Main machine is AT89S51 , lower machine is AT89C2051. they communicate with each other by RS485 bus. And the main machine deploy LCD, keys. The control system easy to install, system is reliable and good maintainability.