This study aimed to investigate the effect of using computer multimedia on grade seven students' academic achievement of the grammatical rules prescribed to them. The sample of the study of the study consisted of (59) students, who were divided into two groups. The first is the experimental group which consisted of (30) students, who studied Arabic grammar rules using of multimedia software (program). The second one is the control group, which consisted of (29) students who studied Arabic grammar rules in the usual way. To achieve the goals of the study, the researcher designed a multimedia program for four grammatical lessons(transitive and intransitive verbs, the subject, the object, and the substitute of the subject). The program included a range of computer multimedia that served the content of the four grammatical lessons. To measure their impact, the researcher prepared a achievement test whose validity was checked by a number of examiners, and its reliability was checked using Cronbach's Alpha coefficient, reaching ratio of (0.078). Results of the study have showed that there are statistically significant differences at (a < 0.05) between the mean scores of the experimental group, that studied the use of multimedia software, and degrees of the control group, that studied Arabic grammar rules in the usual way in the post achievement test of grammatical rules, in favor of the way of multimedia software. In light of the previous result, some recommendations have been suggested including: the need for cooperation and coordination between the Department of Education Technology, and the Department of the Curriculum Development of Arabic language in the Ministry of Education in order to design multimedia programs of various grammatical lessons in the Arabic language books. Other suggestions have been made for further research including: the study of the impact of multi-media programs on the performance of the first cycle of basic education students of the linguistic patterns prescribed to them.