This paper investigated the photochemical behavior of diphenolic acid (DPA) in the presence of beta-cyclodextrin (CD) and TiO2 suspensions under a 250 W metal halide lamp (lambdages 365 nm). The interaction of DPA with CD yielded the formation of inclusion complexes at 1:1 stoichiometric ratio in solution. The irradiation of DPA and TiO2 suspensions in the presence of beta-CD showed that the photodegradation rate of DPA was enhanced. The photodegradation of 10-80 mumol/L DPA in suspended solutions was found to follow the pseudo-first-order law. Obviously, the photocatalytic degradation reaction rate constant of DPA in the system containing beta-CD is higher than that without beta-CD. The adsorption isotherms of DPA could be plotted with the Langmuir isotherm model, and the maximum adsorption capacity increased in presence of beta-CD/TiO2. The influence factors of beta-CD concentration, DPA initial concentration on photodegradation of DPA were studied in details. This paper also simply explored the mechanism of the photocatalytic degradation effect in the presence of beta-cyclodextrin. With the addition of beta-cyclodextrin, the enhancement of photodegradation of DPA mainly results from the enhancement of adsorption of DPA on TiO2 surface and the lower bond energy between some atoms in DPA molecule after inclusion interactions with beta-CD. This could be a promising method for contaminated water remediation.