The aim of this study is to provide the basis for scientific supervision of quality and safety of aquatic products through the survey and source analysis of semicarbazide background value in shellfish. The content of semicarbazide background value in shellfish were determined by using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Among 4 kinds of shellfish, the detection rates of Macrobrachium nipponense and Macrobrachium rosenbergiideman reached 100%. The average detection value of semicarbazide in Macrobrachium nipponense and Macrobrachium rosenbergiideman were 6.92 and 2.52 μg/kg, respectively, both of which exceeded the current residue limits. The contents of semicarbazide in Penaeus vannamei and Eriocheir sinensis were relatively lower. The result of this survey provides data support for formulating the residue limits of semicarbazide in shellfish. ［Chinese Fishery Quality and Standards, 2016, 6(6):6-11］