The research aimed to: reveal the effectiveness of a training program based on the learning by design approach to develop the planning skills of a science teacher during preparation. The researcher used a one-group (experimental) design on (46) science teachers during preparation in the English Eductioonal Physics Department at the Girls' College.The research experimentation tools were (a training program based on the learning by design approach - a trainer's guide (the trainer), activity sheets), and a measurement tool (planning skills evaluation form in light of the learning by design approach). The research tools were applied pre- and post-application to the research group, then the research data was processed statistically, and the research results resulted in the presence of statistically significant differences at the significance level (0.05) between the average scores of science teachers during preparation in the pre- and post-applications of the planning skills assessment form. The whole and each of its dimensions for the benefit of the dimensional application.