Abstract: In order to realize the accurate detection of water needs information in process of tea tree growth and the automatic control of accurate irrigation of tea garden，a system with Cortex-M3 as the core was designed，and the data were stored with two methods of SD memory card and server. The automatic control system used GPRS for data transmission. The system could realize automatical monitoring and regulating for water demand of tea tree at different growth stages. The experimental results show that the system is reliable，simple to operate and has strong expansion ability；it has good market application prospects.

Key words: STM32, GPRS, humidity, tea tree