The CAI (Computer-Assisted Instruction) system for science teaching has been increasing both in quantity and in quality during the last two decades. However, science learning by computer has not played a leading role in the science teaching process. Therefore, the purpose of this study was to analyze the effectiveness of tutorial CAI programs according to the learner's characteristics such as sex, inquiry skills, scientific attitudes, logical thinking skills, achievement motivation, science content achievement in science teaching. One group pretest-posttest design was used as an experimental design. The three tutorial science CAI programs were used for thirty males and females selected in grade eight. According to the analysis of CAI achievement scores the female students showed significantly higher (P$lt;0.05) than the male students. Also one-way analysis of variance was used to investigate the effects of interaction between sex and achievement motivation. The significant difference on the effects of interaction between sex and achievement motivation has not found. The effects of tutorial CAI between logical thinking skills, scientific attitudes, inquiry skills, achievement motivation, science content achievement according to upper and lower levels were investigated by using the statistical analysis of one-way ANOVA. The results indicate that tutorial CAI might provides a good opportunities for the improvement of science achievement to the lower level students of science attitudes, inquiry skills, science content achievement.