Environment Changes due to temperature, humidity, wind loading and so on can affect the performance of a large telescope. The real-time information of environment change must be got in order to exert control, reduce or eliminate the adverse effects of environment changes on the large telescope. A novel method of environment monitoring for a large telescope based on wireless sensor networks has therefore been proposed to realize environment data acquisition, on-line-detection and data analyzing in this paper, which provides the basis for the adjustment of the large telescope to improve its control performance and image quality.