Abstract: Aiming at overcoming the shortcomings of the design methods of agricultural monitoring system, a new approach was investigated to develop greenhouse environment monitoring systems where air temperature, air humidity, CO2 concentration can be online measured and monitored. A fundamentally different embedded system design method named Joint-Debugging of Proteus and Keil was proposed, which significantly reduced the development cycle and hardware costs. C# language was adopted to develop PC monitoring software and Access Data Base was used to store and manage the historical data. Several system key issues including key data processing, serial interrupt data-flow building, Access Database design, Proteus and PC communications were well solved. The experimental results show that the system runs well and verifies the effectiveness of the proposed methods.