Nowadays, the research of focused crawler approaches the field of semantic web, along with the appearance of increasing semantic web documents and the rapid development of ontology mark-up languages. Semantic focused crawlers are a series of focused crawlers enhanced by various semantic web technologies. In this paper, we make a survey in this research field. We discover eleven semantic focused crawlers from the existing literature, and classify them into three categories – ontology-based focused crawlers, metadata abstraction focused crawlers and other semantic focused crawlers. By means of a multi-dimensional comparison, we conclude the features of these crawlers and draw the overall state of the art of this field.