The study aimed to investigate the effectiveness of using inquiry and brainstorming strategies in teaching Arabic language for developing achievement and creative thinking skills of the university students. To achieve the previous objective, a teaching manual was prepared using inquiry and brainstorming strategies. Achievement test was prepared including 20 items multiple chooses questions related to knowledge, application and reasoning levels. In addition, creative thinking skills test was prepared including 10 items related to Fluency, flexibility and originality skills. The validity and reliability of the instruments were measured. The sample was selected randomly; it consists of two groups, experimental group 43 and a control group 39. The study was based on semi-experimental design pre—post-test, where the experimental group was taught using inquiry and brainstorming strategies, but the control group was taught using the usual strategies. The results of the study showed that there were statistically significant differences between the average scores of the experimental and control groups in the post achievement and creative thinking skills in general and their skills separately for the students of the experimental group. Also, the results showed a positive correlation between the scores of the experimental group in post creative thinking skills, and post achievement test in general. The effectiveness of inquiry and brainstorming strategies in the development of achievement levels and creative thinking skills was significant effect. The study recommended using the Inquiry and brainstorming strategies in the teaching Arabic language of university students.