The paper uses an important event happened in Chinese health consulting market in 2010，i.e. Zhangwuben event, to conduct an exploratory case study. Using the abundant secondhand materials circled on Zhangwuben event, the paper identifies successfully the dimensions of knowledge quality assessment, and finally builds out the model of knowledge quality assessment, which uses signal, process, ontology and application dimensions totally containing 16 assessment items to assessment knowledge quality. This model is supported soundly by the experience data and provides a base to further knowledge quality theory. Also this model means some important strategy for knowledge transaction and government to govern knowledge markets.