The invention relates to a 
building energy-saving 
casement window structure with anti-mosquito and anti-falling functions for children. The 
building energy-saving 
casement window structure comprises an outer frame, a protective guard, an invisible screen window 
assembly and at least one movable window sash, the outer frame is of a broken bridge structure with an inner 
flange and an outer 
flange, an inner 
flange sectional material is arranged on the inner flange, an outer flange sectional material is arranged on the outer flange, and the invisible screen window 
assembly is arranged on the outerflange sectional material; a plug is arranged on the outer frame, and a fastening rubber strip is arranged in the position, corresponding to the plug, of the protective guard; and the invisible screen window 
assembly comprises an upper rail, a lower rail, a screen, a 
handle, a screen box and a screen drum, a 
damper assembly is arranged at the top of the screen box, and a lower box cover rotatingmechanism assembly is arranged at the bottom of the screen box. The energy-saving 
casement window structure is suitable for refitting energy-saving 
doors and windows of newly-built buildings and existing residential buildings (installed or delivered houses), the 
building energy-saving casement window with the functions of preventing mosquitoes and preventing children from falling is formed, the structure is stable, and the cost is low.