An introduction is made to the application of the RS485 bus in the nearsurface layer flux observation system at Zhangye, as well as the characteristics, working mode, and networking of the RS485 bus, which consists of there subsystems: eddy covariance system, gradient system and wind energy observation system. About oneyear application of the RS485 bus at the Zhangye National Climatological Observatory indicates that it is stable, has good antinoise capability, and can be used in longdistance data transfer.