A new method is proposed that utilizes the quantum beat of polarization anisotropy in two-photon ionization of atoms and molecules. It was shown that the frequency and the amplitude of the beating anisotropy contain information on, respectively, the hyperfine constants of the electronically excited state and the branching ratio of the photoionization channels leading to different photoelectron angular momentum states in the ionization continuum. The method was demonstrated for the case of the Na 3p P-2(3/2) state by the time-resolved two-photon ionization with two pulses of parallel and perpendicular polarizations.