Introduction: Intrauterine Contraceptive Devices (IUD) is a contraceptive device that inserted into the uterus. In Municipality Dili, IUD use is 5.6% and in Community Health Center (CHC) Comoro about 3.4. The aim of this study was to determine the influence of acceptor knowledge and attitudes on the low practice of using IUD at Comoro Community Health Center. Method: The quantitative design-cross sectional approach was used in the study. Total population about 2881 family planning acceptors who did not use the IUD contraceptive method visited CHC Comoro. About 106 respondents was included, used accidental sampling technique. Data collected use questionnaire and analyzing used univariate and bivariate. Result: The multiple linear regression test on the Knowledge are 0.016 < 0,05, which means that there is a partially significant influence of Knowledge on practice and attitude is 0.003< 0.05, which means that there is a partially significant influence between attitudes on practice. The correlation value on the F test was 0.00< 0.05, meaning that there was a significant simultaneous influence between Knowledge, attitude on practice. Conclusion: There is an influence of acceptor’s Knowledge and attitude on the practice of IUD contraceptive use partially in partially and simultaneous.