Abstract: Na-montmorillonite (Na2MMT) was exchanged with Cu²⁺ and t ributyltet radecyl phosphonium cation( TBTP) in turn by the ion2exchange method. The mass f ractions of TBTP and Cu²⁺ were 24. 07 % and 2. 87 % ,respectively. The result s of TG and XRD show that Cu²⁺ and TBTP have been exchanged in montmorillonite , andthe onset decomposition temperature of the quaternary phosphonium cation is about 220 ℃. The antimicrobial experiment indicates that the montmorillonite composite materials ( TBTP-Cu/ MMT) possess wonderful antimicrobialactivity and the minimal inhibitory concent rations (MIC) are 12. 5μg·mL^-1 and 200μg·mL^-1 against S. aureus andE. col i , respectively. The influences of the concent ration of TBTP-Cu/ MMT and contacting time with bacteria onthe antimicrobial activity of the modified montmorillonite were studied. The result indicates that their antimicrobialactivities increase with increasing the concent ration and contacting time with bacteria. After 100 mg TBTP-Cu/MMT being soaked in water for 20 days , the release amount s of TBTP and Cu²⁺ f rom the montmorillonite composite materials are only 41891 mg·L^-1 and 1. 928 mg·L^-1 , respectively.