For better efficiency and accuracy, it needs semantic match between grid services to implement the service discovery, the service query, and the dynamic allocation and replacement of service. An ontology-based semantic service component of the Image Processing Grid Platform is introduced in this paper. The framework of this component is firstly described and the core semantic match algorithm is given subsequently. The semantic service component implements the semantic query of grid service, the automatic semantic match for workflow construction, as well as the dynamic allocation and replacement of grid service when workflow is running. Finally, the experimental results show that the proposed algorithm has better accuracy than the classical semantic match algorithm for the grid service matching.