Although statistical characteristics of audio features are widely used for similarity measure in most of current audio analysis systems and have been proved to be effective, they only utilized the averaged feature variations over time, and thus lead to inaccuracy in some cases. In this paper, structure pattern, which describes the representative structure characteristics of both temporal and spectral features, is proposed to improve the similarity measure for audio effects. Three kind structure patterns are proposed and utilized in current work, including energy contour pattern, harmonicity pattern and pitch contour pattern. Evaluations on a content-based audio retrieval system indicate that structure patterns can improve the performance pretty much. Categories and Subject Descriptors H.5.5 [Information Interfaces and Presentation]: Sound and Music Computing - signal analysis, synthesis and processing; I.5.1 [Pattern Recognition]: Models - structural General Terms Algorithms, Measurem...