The information asymmetry between buyers and sellers exacerbates adverse selection in the edible agricultural products market. The fundamental cause is that edible agricultural products have significant characteristics of credence goods, which makes it difficult for consumers to directly judge their quality grades even after using. The role and mechanism of product quality signals on adverse selection were theoretically elaborated. Furthermore, an empirical study was conducted to test the hypothesis using survey data from the tea products market which is a typical edible agricultural market segment. The results showed that promoting the release of product quality signals mitigated adverse selection due to information asymmetry. The intensity of the effect of external quality signals was higher than that of internal quality signals. In the meantime, moderators which are market activity and information matching efficiency, would affect the strength of the effect of product quality signals release on adverse selection. Therefore, it is necessary for enterprises, third-party institutions and relevant government departments to collaborate to promote the effective release of internal and external quality signals of edible agricultural products, improve the construction and disclosure system of product quality information, thereby alleviating the adverse selection and promoting the formation of a unified national market for edible agricultural products.