The invention discloses a glass fiber cement non-removal formwork system, a connection structure and a construction method of the connection structure. The formwork system comprises a panel group, a support frame structure and a split bolt, wherein transverse interlocked strengthening grooves are formed in the inner side surface of a panel unit at intervals; the support frame structure comprises a frame steel sheet strip, a cross-panel connection assembly and a telescopic panel-attached brace; the frame steel sheet strip is arranged in a full length along the height direction of the panel unit; the cross-panel connection assembly comprises a one-way cross-panel connector; and the split bolt passes through the one-way cross-panel connector and tightens the formwork system from front to back. The connection structure comprises a floor, a formwork bottom locating assembly, a formwork top locator and the glass fiber cement non-removal formwork system. The glass fiber cement non-removal formwork system is simple in form, relatively large in combination rigidity, high in manufacturing accuracy, tight in seam, safe and reliable in structure, good in overall performance, relatively high in turnover frequency, energy-saving and environment-friendly. According to the connection structure and the construction method thereof, the construction efficiency of formwork engineering is improved and the construction cost is reduced.