Abstract: Effects of processing methods(boiling and steaming)on nutritional ingredients(moisture,ash,total sugar,protein,fat,and amino acid)and flavor characteristics of Sipunculus nudus were studied by the national standard detection methods and electronic nose technology. The results showed that boiling and steaming significantly reduced the contents of moisture,ash,total sugar,protein and amino acid(p<0.05),showed no significant effect on fat content(p>0.05). After processing,the contents of amino acid were reduced and the ratios of essential amino acid to total amino acid were significantly decreased(p<0.05),while the ratios of umami amino acid to total amino acid were significantly increased(p<0.05),enhancing the umami taste of Sipunculus nudus. Electronic nose could distinguish the flavor characteristics of Sipunculus nudus before and after processing,with the principal component analysis showed the obvious differences between the samples. Loadings analysis showed that S2,S7 and S9 sensors contributed greatly to the first and second principal components. The contents of flavor components of ammonia oxide,methane,hydrogen sulfide and aromatic alkanes were increased after boiling and steaming,where the content of ammonia oxide and hydrogen sulfide increased obviously. Therefore,both processing methods caused the loss of nutritional contents and flavor changes,which provided references for development of a new technology for processing edible Sipunculus nudus.