The purpose of this study is to know the effectiveness of 3D intermolecular forces multimedia to improve students' learning outcomes. Intermolecular forces are one of chemistry concept that needs microscopic and symbolic representation, thus students needs multimedia that could visualize the microcospic and symbolic representation. This study used one group pre-experimental design. In the data gathering section using one group pretest-posttest for 25 students. The instruments that used are intermolecular forces test sheet as a learning outcome test. The results obtained are a score of learning outcomes. The effectiveness 3D intermolecular forces multimedia assessed from the score increase both learning outcome and classically completeness. The average N-gain for the cognitive test is 0,7 and the classically completeness reach 86,8. According to the average N-gain and classically completeness, the usage of 3D intermolecular forces multimedia gives a positive response to improve learning outcomes.