Abstract: Temperture and humidity auto-control system with fuzzy decoupling for seedling has been designed to improve the quality of mechanical operations and automatic level for seedling. It applied real-time sampling control to unfold or fold the plastic-film shed for the seedling bed automatically according to the real-time changes of temperature in the seedling bed. It could also irrigate the seedling bed or stop irrigating automatically according to the real-time changes of soil water content of the land. In order to solve the phenomenon of cross-coupling between temperature and humidity. The decoupling factors φ1, φ2 had been introduced and the fuzzy control algorithm with decoupling adopted in it. The practice shows this system operates reliably and stably, and it can better meet the seedlings’ technical demands for the temperature and humidity.