To completely raise the monitoring, forecast and control technology of pest diseases during tobacco cultivation management process, we make use of Silverlight and Windows Communication Foundation (WCF) technology to construct the early alarm system of tobacco pest diseases based on service-oriented B/S model. The technology of Silverlight is used to produce the early warning trends map of the tobacco pest diseases and draw the trend line of the pest diseases in the browser, which plays a key role in guiding diagnosis of disease more scientific and release of prevention measures for experts. The server use layered structure, and realize data access through WCF. The system not only satisfies the tobacco management department’s business demands, but also enrich the user’s experience, meanwhile, it also enhances the tobacco management department’s working efficiency and decision support level.