The study evaluates germicidal effects of titanium dioxide photocatalytic filter and ultraviolet on bioaerosols. The experiment used a testing chamber to simulate an indoor HVAC system and four bioaerosols. The influences of microorganism species, UV length (365 nm, 254 nm), relative humidity (30%, 60%), and filters (uncoating and Degussa P25 TiO2 -coated filter, D-type TiO2 filter) on the germicidal effects with ACH are 1 h-1 and fresh ACH are 0.18 h-1. A Collison nebulizer generated Escherichia coli (E. coli), Bacillus. subtilis (B. subtilis), endospores, yeast cells of Candida famata (C. famata) var. flareri, and spores of Penicillum citrinum (P. citrinum). The viable bioaerosol concentration collected by Anderson one-stage sampler passed through TiO2-coated filters with and without ultraviolet irradiation. The filtration mechanism, PCO process and germicidal effects was determined as the parameters, decay constant (kn, ka-d, and ka-l), CADR(Qi), and removal efficiencies（η）. Besides the parameters, we also investigated the proportion of filtration, ultraviolet irradiation, and PCO process. The experiment results demonstrated that PCO process wasn’t significant in HVAC system. In a word, with the 254 nm ultraviolet and photocatalytic filter, the removal efficiency would be increasing obviously. Raising the relative humidity in the control mechanism didn’t effects apparently. In a comparison of TiO2 filters, the difference of the results were also unobvious. It showed that the removal efficiency of E. coli are the best with the 254 nm ultraviolet and photocatalytic filter in HVAC system.