Abstract: Stable δ¹³C and δ¹⁵ N is a very effective technology used to research material circulation and energy flow in ecosystem. The δ¹³C value is commonly used for the analysis of consumer food source. The δ¹⁵ N value is commonly used to determine the living creature position in the food web. Stable δ¹³C and δ¹⁵ N are used to to research the trophic level relationship of Guizhou Shibingxia cave and Mulaotang cave. The result showed that fauna enrichment on the δ¹³C and δ¹⁵N enrichment were obvious in Shibingxia cave and Mulaotang cave. Two caves enrichment spans on the δ¹³C (the difference between the maximum and minimum values) were 4.911 4‰ and 6.292 8 ‰ respectively and on the δ¹⁵N were 6.687 0‰ and 5.056 0‰. But on the whole, the two ecosystems enrichment on δ¹⁵N is much stable than on δ¹³C. So it is concluded that the two caves enrichment factors on the δ¹⁵N value are 2.808 0 and 2.420 0 respectively by using the level δ¹⁵ N value to evaluate the level of nutrition. The trophic levels have three levels. They are as follows. The first trophic level is soil organic matter. The second trophic level is Kronopolites sp., Gastroptychia sp. and Distrammena sp. which feed on soil organic matter. The third trophic level is Oreolalax rhodostigmatus, spiders and bats taxa.

Key words: δ¹³C, δ¹⁵N, trophic leve, Shibingxia cave, Mulaotang cave, Guizhou,China