The purpose of this study was to investigate psychometric aspects (reliability and validity) of this test set in 7-9-year-old Tehrani children. The research method was descriptive and cross-sectional research design. A total of 234 children aged 7-9 from Tehran, Iran were selected randomly from three regions of western, central and southeast of Tehran. The tool for this study was the TGMD-3 test suite. For data analysis, the statistical methods of confirmatory factor analysis were used using structural equation modeling (SEM), Cronbach's alpha, intra-class correlation coefficient, Pearson correlation coefficient and paired t-test. The internal consistency of the subtest of ball test, displacement and total test for girls was 0. 74, 0. 78 and 0. 77 for boys respectively 0. 69, 0. 85 and 0. 78, respectively, and the reliability of the test-retest was 0. 84, 0. 73 and 0. 79 respectively. The reliability coefficients within the evaluator of the hub, displacement and total test were 0. 89, 0. 92 and 0. 91 respectively and the reliability of the evaluators was 0. 85, 0. 89 and 0. 87, respectively. Structural validity, Ulrich's two-factor model was confirmed through confirmatory factor analysis. Correlation coefficients between age and scores of sub-tests were significant and moderate. Structural reliability coefficients for ball and displacement subscales were 0. 74 and 0. 71 respectively, so the test and its subscales have good structural reliability. Considering the confirmation of both the reliability and validity of the TGMD-3 test, it can be safely used to test and assess the development of large motor skills in 7-9-year-old children in Tehran.