Lack of physical activity is one of the main concerns about children's public health. Physical environment is one of the variables that seems to affect the level of physical activity. The Purpose of this study was to construct and validate competency scale for evaluating physical features promoting the physical activity of children in the school yard. The statistical population of the study was children aged 8 to 11 years old in Tehran. Sampling was done in a multi-stage cluster sampling, and 120 selected children participated voluntarily in the selected areas. The method applied in this research was descriptive-correlation. Content validity of the questionnaire was confirmed by an expert university panel, its face validity was confirmed by a group of children and construct validity was evaluated using the confirmatory factor analysis. Based on exploratory factor analysis with varimax rotation, 21 items were divided into 3 factors. Total variance of these factors explained% 53.858 variance of physical features. According to experts, the resulting agents were called "environment attraction", "community spaces" and "play development". The findings of this study identify the most important physical variables that affect physical activity in the school yard, so it can be used to design the school yard.