Background: The purpose of this paper is to identify the values of some biomechanical variables for the starting phase, swimming, and completion of the 50-meter freestyle swimming, and identify the effect of using a device (the launch angle changer for the starting stage of swimming) on some of the biomechanical variables affecting the starting stage of 50m freestyle swimming. Methods: The researcher used the experimental approach using the experimental design method (pre and post-test for one group) due to its suitability to the nature of the research problem. The selection of the research sample came within the basic and important points in the research procedures, which the researcher adopts to reach results with high credibility. Therefore, the researcher chose six swimmers representing (100%) of the origin community, and they are the players of the Iraqi national team, category (13 - 15) years old in the 50-meter freestyle swimming event. Results: The change in the kinematic variables of the starting phase showed significant differences, which contributed to the development and increase of the swimmer, is starting speed, and the change in the kinematic variables of the starting stage showed significant differences, which contributed to the development and increase of the horizontal distance achieved. One of the most important recommendations is that: increasing focus on the starting stage of swimming during training and including it within the training units for its effective role in improving the level of achievement, and the use of auxiliary tools and devices that help detect weaknesses and enhance strengths, which facilitate the coach's task in developing swimmers