The invention provides a closed graph similarity search method based on time sequence complexity difference, which comprises the following steps: S1, observing a closed graph to obtain a time sequenceof the closed graph; S2, setting the complexity difference CO of the two time sequences; S3, setting a complexity time measurement standard TSD; S4, finishing neighbor search on the complexity time measurement standard in the S3 by adopting an exhaustion method; S5, correcting the distance value by adopting a triangular inequality; S6, obtaining a closed position of the two-dimensional relative graph in the serialized index data structure; the problem that an existing graph similarity search method cannot achieve similarity search of two-dimensional graphs is solved. Meanwhile, the time dimension of a time sequence is greatly solved, the effectiveness of graph rotation in the measurement process is ensured, measurement standards are given for time sequences with different complexity degrees, and finally similarity search of two-dimensional closed graphs is achieved.