Design-by-Analogy (DbA) is a powerful approach to innovative conceptual design. Cross-domain analogies are the stimulated sources of inspiration for generating new concepts. Therefore, how to efficiently retrieve them becomes an essential issue to be solved. This paper proposes a tool based on a structure-mapping function model (SMFM) for analogy retrieval. Inspired by the structure-mapping theory, SMFM considers two in-depth features: functional relation and causal relation between functions, which are expressed by function and meta-function concepts, respectively. SMFM serves to capture design knowledge from instances (i.e., engineering or biological systems) to establish a case database. The SMFM ontology is constructed for linking knowledge representation and analogy retrieval. Its meta-function, function, and flow terms are used to index the modeled instances so as to establish an index database. Analogy retrieval is realized by the ontology-based query expansion, vector space model and weighted cosine similarity. By inputting function or meta-function queries, we retrieve the required cross-domain analogies, whose design knowledge is displayed by function models to inspire target functions or meta-functions realization. Finally, the tool is evaluated for its effectiveness in cross-domain analogies retrieval. An application example illustrates its practicality in aiding innovative design. Additionally, an experiment was conducted to test the tool. The results indicate that our tool can assist users (e.g., engineering designers) to more quickly generate new schemes to realize target meta-functions and the quality of schemes is higher.