Purpose. To determine the peculiarities of 9-year-old girls’ motor fitness structure. Materials and methods. The study involved 35 9-year-old girls. The children and their parents were informed about all the features of the study and gave their consent to participate in the experiment. The study used the following research methods: analysis of scientific and methodological literature, pedagogical observations, testing of motor fitness, probabilistic approach to assessing the learning process, methods of mathematical statistics. Results. The level of fitness of the 9-year-old girls is homogeneous by the development of “agility” and “movement coordination”, inhomogeneous – by the development of flexibility, arm strength, vestibular stability, and the level of proficiency in gymnastic exercises. A graphic representation of a two-factor model of testing results shows that the analysis identifies two sets of data with high correlation coefficients. The first set includes tests No. 12, 13, 14, and 7, which characterize the level of proficiency in gymnastic exercises and relative arm strength; the second – tests No. 1, 10, and 5, which characterize the level of movement coordination development. Conclusions. Based on factor analysis, it was found that the level of proficiency in exercises determines the variation of testing results by 28.394%, and the development of motor skills is a priority in the educational process at primary school. The level of proficiency in gymnastic exercises shows that the exercises “Rope climbing in two steps”, “Rope climbing in three steps”, “One leg swing upward circle” are difficult for 9-year-old girls to perform. Based on the data analysis, it can be argued that the development of “arm strength” and “vestibular stability” ensures the formation of motor skills, and the improvement of their development level is the reserve in training girls aged 9 which will positively influence the formation of motor skills.