The current research aimed to develop the EFL descriptive writing performance and of secondary stage students and to find its effect on their self-efficacy. Reaching this aim, the present study followed the pre-post, experimental and control group design. The researcher used two groups; experimental and control groups. Conducting this treatment, a number of sixty EFL second secondary stage students from Al-Ibrahimia Secondary school, Ibrahimia Directorate, Sharkia Governorate, Egypt, were randomly assigned in two groups, thirty students for quasi-experimental group and thirty for the control group, the researcher applied a pre and a post –test for the purpose of data gathering and analyzing .      The researcher designed an EFL descriptive writing test to measure EFL descriptive writing performance level before and after the treatment, a scale was designed for measuring the effect of the integrative strategy based on task based learning and peer discussion on the students' self-efficacy. The instruments were administrated before and after the treatment. Generally the current study was conducted over a period of ten weeks over the first term of the academic year 2022-2023. Finally, the results of the study showed that the integrative strategy based on task based learning and peer discussion has positive effect on developing the EFL descriptive writing performance of the secondary stage students and on their self-efficacy.