In this paper the reverse saturable absorption (RSA) in the organic material ZnTBP/CA/PhR is reported. The energy-level is studied using the rate equation theory and it is found that the absorption cross section of the first excited triplet state should be bigger than that of the ground state in RSA process. It is proved by the experiment in which an Ar+ laser and a dye laser focused onto the sample together. The RSA in this material can be operated with a continuous-wave laser of moderate energy.