The system of library temperature monitoring is designed basing on a micro-power data transmission model. The distributed network constitutes some temperature data collection sub-systems and a monitoring center to realize real-time data processing by using model FC-210S.This paper decribes at length the components and the design method. The error of the temperature monitored is within ±0.1℃. Critical temperature alarming and historical data can also be obtained in this system for present and future need.