VSTO 2005(Microsoft Visual Studio 2005 Tools for the Microsoft Office System) are bulit-in tools, which are used to develop the solution of Office. This paper proposes an intelligent documents technology based on VSTO, and implement the integration of the Office and the management information system. It was successfully applied to the investigation of the state of environmental protection of the enterprises. Various enterprises users may fill the information on the familiar Office interface, avoiding filling the information on the papers. With the documents variable we set documents condition and implement documents "signature". So the presented technology may guarantee the accurateness, validity and security of the stored enterprise information. Also it can promise the dependability of the print and analysis processes. This system can reduce the cost of the server resource during collecting information in network. The running results of this application system show it has important practical significance and application value.