Abstract: Rare earth elements are wide-used in China, but a few of studies were made on whether they had toxicity to soil fauna.In this paper, the filter paper contact method was used to study the influence of two rare earth elements on the dynamics of amino acids in earthworm body.The result showed that at low concentrations, the test rare earth elements increased the amino acid contents except proline, but decreased them at high concentrations.The amino acid contents began to increase at 400 mg· L^-1, while decreased with time.Both of the two rare earth elements reduced the proline content, and behaved inhibition effect at the range of 100～1200 mg·L^-1.