A curved brace edge connection fitting and a curved brace window sash edge connection fitting and a window structure are provided. A coupling intensity of existing modular edge connection fittings can be heightened to simultaneously enhance air-tightness and heat insulation and to further provide effects of curved design and easy cleaning. The curved brace window frame edge connection fitting and the curved brace window sash edge connection fitting are used in a push-to-open window called a slider and a rotate-to-open window called a casement.