The existing vectorization methods are used for lines, arcs and circles, but they still rarely involve in small feature raster graphics. In this paper, we present a mini arc recognition algorithm based on the topological inference, which infers the mini arc by the topological characteristics of raster graphics. The zone of influence is defined and its calculational methods are given to build the topological adjacency relation graphs between the vectors. The data structure is also depicted for storing and using the topological adjacency relations of vectors. Then we define the topological inference rules for mini arc, by which we can infer and recognize the mini arc. We also experimentally evaluate our algorithm by using benchmark data and real drawings. The result of the experiments indicates that the algorithm is fast and effective.