This paper addresses the design of a synthetic environmental monitoring system based on Mesh wireless sensor network to find out the laws of the environmental change and harmful gas emission in the pig farm. This monitoring system provides long-time,multi-point,real-time environmental data of the piggery.Within the Mesh network, the number and the variety of the sensors can be improved with reliable communication. DSDV-routing-protocol-based multi-hop transmission is realized on TinyOS. Software for remote visit and monitoring of the data of the pig barns through internet is designed by using database and network technology. Experiments in nursery barn show the steadiness of the system, which realizes functions such as information selection,real time monitoring,remote visit and data storage. These provide efficient data for pig barn environmental researches.