Abstract: The paper aims to verify the control efficacy of predatory mites against thrips at tobacco seedlingstage. The authors investigated the occurrence and species of thrips and comparatively studied the control efficacy of release quantities, methods and carried microbial agents of different predatory mites in Zhongshu, Luxi, Yunnan. The results showed that: the main species of thrips was Frankliniella occidentalis (Pergande), followed by Thrips flavidulus (Bagnall), the thrips reached the highest peak in mid-April; the release of 100 mites Amblyseius cucumeris (Oudemans) per tray provided the best control efficacy among different release quantities, and the uniform broadcast method was significantly (P<0.05) more effective than placed with an open bag and CK; the control efficacy of predatory mites carried with Beauveria bassiana Vuillemin was the best, and the control efficacy of predatory mites carried with Metarhizium anisopliae Sorokin were parallel to that without microbial agent, whereas both were significantly more effective than CK (P<0.05).