The utility model relates to a slipping landing system and a slipping landing method for segmental steel box girders. The slipping landing system adopts the following structure that transversely slidable slides 2 are positioned on fixed slides 1; the longitudinal and transverse difference of elevation among the transversely slidable slides 2, the fixed slides 1 and the top surface is not greater than plus and minus 5mm; the transversely slidable slides 2 are positioned on lower slides 9; a bridge deck girder erection crane 6 and a transportation pontoon 7 are correspondingly arranged; the segmental steel box girders 8 are positioned on the transportation pontoon 7; when the bridge deck girder erection crane 6 lifts up the steel box girders 8 on the pontoon 7 to leave from the slides by 50cm, the transportation pontoon 7 pulls out; a slipping bracket is formed by steel pipe piles 5 and the slides; the slides consist of BeiLei beams 3 and slide beams 4; the bridge deck girder erection crane 6, the steel box girders 8 and a sliding block 10 are correspondingly arranged. The slipping landing system and the slipping landing method have the advantages that large-scale lifting and transporting equipment does not need to be additionally configured; the bridge deck girder erection crane is directly utilized to enable the segmental steel box girders to be lifted up from the pontoon and slide to positions where the segmental steel box girders are to be erected; the slipping landing system and the slipping landing method are rapid and convenient to operate; engineering cost is reduced.