The invention relates to a multifunctional folding chair which comprises a backrest, armrests, a cushion, chair feet, a foot rest, a outer slideway, a slider, universal wheels, an airbag, a thrust bearing seat and a backrest support. The backrest is connected to the cushion, the backrest and the cushion can be unfolded and folded, the foot rest slides in or out along an inner slideway inside the cushion, the outer slideway is arranged at the bottom of the cushion, the slider is buckled in the outer slideway, multiple pin holes are formed in two sides of the outer slideway, and the slider and the outer slideway are positioned through elastic pins and the pin holes; two ends of the armrests are respectively connected with the backrest and the slider, a thrust bearing and the thrust bearing seat are arranged at the bottom of the slider, the upper end and the lower end of the airbag are respectively connected with the thrust bearing seat and the chair feet, and the universal wheels are mounted on the chair feet. A chair or half-lying chair or lying chair or folding chair can be formed by adjusting the backrest, the cushion, the foot rest, the outer slideway and the slider, so that the chair is multifunctional, simple in structure, convenient to use and saving of space and public resources.