In this work, a series of polyphenol porous polymers were derived from biomass polyphenols via a facile azo-coupling method. The structure and morphologies of the polymer were characterized by BET, TEM, SEM, XRD, TGA and FT-IR techniques. Batch experiments demonstrated their potentialities for adsorptive separation of Cs+ from aqueous solution. Among them, porous polymers prepared with gallic acid as starting material (GAPP) could adsorb Cs+ at wide pH value range effectively, and the optimal adsorption capacity was up to 163.6 mg/g, placing it at top material for Cs+ adsorption. GAPP exhibited significantly high adsorption performance toward Cs+ compared to Na+ and K+, making it possible in selective removal of Cs+ from ground water in presence of co-existing competitive ions. Moreover, the Cs-laden GAPP could be facilely eluted and reused in consecutive adsorption-desorption processes. As a result, we hope this work could provide ideas about the potential utilization of biomass polyphenol in environmental remediation.