Abstract: The present invention discloses a cast-in-place protective sheet, comprising the main ingredient taking up 45%-95% of the total by weight, which is composed of 125-140 parts of isocyanate, 10-220 parts of polyamine compound, 220-660 parts of diamine compound, 210-260 parts of polyether diol and 115-190 parts of polyether polyol, as well as the excipient taking up 5%-55% of the total by weight which is composed of 20-140 parts of environmental diluent, 1-35 parts of organometallic catalyst, 30-400 parts of filler and 4-75 parts of deforming agent. The present invention is an environmentally-friendly seamless waterproof material which has the advantages of strong adaptability to the environment, fast curing and good flexibility.