Abstract: The Onsager s reciprocity relation takes the important role in the development of linearity nonequilibrium thermodynamics.The relation reduces difficulties and workload in experiment analysis so as to offer possibility to definite the phenomenological coefficient.This paper proofs the relation from independent variables：temperature,volume and temperature,number of particle,and investigates entropy production rate physics innate character,respectively.

Key words: Onsager s reciprocity relation, fluctuation, phenomenological coefficient