Focused crawling is proposed to selectively seek out pages that are relevant to a predefined set of topics. Since an ontology is a well-formed knowledge representation, ontology-based focused crawling approaches have come into research. However, since these approaches apply manually predefined concept weights to calculate the relevance scores of web pages, it is difficult to acquire the optimal concept weights to maintain a stable harvest rate during the crawling process. To address this issue, we propose a learnable focused crawling approach based on ontology. An ANN (Artificial Neural Network) is constructed by using a domain-specific ontology and applied to the classification of web pages. Experiments have been performed, and the results show that our approach outperforms the breadth-first search crawling approach, the simple keyword-based crawling approach, and the focused crawling approach using only the domain-specific ontology.