In this research, the effectiveness of Computer-Assisted Instruction on Academic Achievement of Higher Primary School in Ahwaz City has been surveying. Two hounded students (boys and girls) randomly selected and in each school, two classes (50 students in each class and totally four classes), were divided with the same teacher in science subject. It has collected around 200 academic achievement scores in science subject in form of pre-test and post-test from two different groups (control and experimental group). Pre-achievement scores in science in previous semester and non-verbal intelligence scores have obtained as co-variates for the study. It has analyzed the results that has compared between two groups with respect to academic achievement in science subject. The results revealed that the Computer-Assisted Instruction software package has its effect on academic achievement in science subject of students in experimental group and scores of students in experimental group were higher than scores of students in control group. In addition, the results revealed that there is no significant difference between boys and girls in academic achievement scores in science of experimental group after implement the Computer-Assisted Instruction software package teaching method and both of two groups have higher scores in science subject.