Abstract: Taking current biological model as an example, the life-effects on environmental elements and stable isotopes and their change tendencies of different times are discussed by a comparison of element contents and isotope compositions of the second layer of in-situ-buried brachiopoda Rhynchospirifer and their host rocks from different strata of the Givetian Period,Middle Devonian, Liujing section. The coeval life-effects on the environmental elements are discussed by a comparison of element contents of the second layer of in-situ-buried brachiopoda Rhynchospirifer and Stringocephalus and their host rocks from the same life environment. Responding to the changes of environmental elements, the Rhynchospirifer had different changes for different elements. This is because that, on the one hand, it had different ecological amplitudes and endurances for different elements, on the other hand, with the time span from the Lower varcus to the Middle varcus, its in-genus evolution had some consequence to its in-genus specific selectivities. Rhynchospirifer and Stringocephalus kept a higher in-genus effective and specific selectivities on their narrow endurancing elements such as Al, K, Sc, Co. Their specific selectivities were limited or some times overlapped by effective principle and abundance effect to the moderate physiological effective and endurancing elements such as Mn, P, Ni,Cu. For the wide ecological amplitude elements such as V, Cr, Sr, Pb, the in-genus specific selectivities were weak. Parts of the ecological amplitudes were overlapped and contents of certain elements such as Mg, Na, As, Pb were even higher than those of the same genus when the two coeval genus shared the same living environment by the way of two nearby niches. The δ13C and δ18O of the second layer of Rhynchospirifer kept good consistence to their host rocks respectively, showing that there was no life effect on the δ13C and δ18O of their living environment.