The greenhouse are classified as complex systems such as large lag, multi-input multi-output (MIMO), non-linear and difficult to create mathematic model and so on, so it is difficult to implement classical control methods for this kind of process. A new sectional-control strategy is put forward. It uses different control modes for different deviation domains. The new strategy is based on MPT intelligent control algorithm which improves on the traditional PID algorithm and adds in self-adapting, fuzzy control, expert self-tuning etc intelligent control functions. When the deviation exceeds a certain domain, fuzzy control is used to prevent the saturated integral; when the deviation reduces to within a certain domain, MPT algorithm is used to reduce the overshooting during response process and eventually eliminate the residual. The application in greenhouse control shows that the sectional-control strategy makes the output tracing the set value correctly.