Abstract: Online sketch recognition for irregular military marking symbols is a significant component of sketch-based military situation marking systems.The shape of an irregular military marking symbol can change much subject to a specific terrain or battle scenario.It is irregular and different with traditional point symbols.A structural recognition method is proposed with three steps.First,the primitives of a symbol are recognized.Then the features of fuzzy topological relations are extracted for every pair of primitives.Next,we build the primitive matching cost matrices between unknown sketched and template symbols,and calculate the matching distances of them with the model of assignment problem.Besides,we propose two techniques to measure the similarity between the partially drawn symbol and templates.Experimental results demonstrate that the proposed methods are effective and efficient.