The invention relates to a special PP (Propene Polymer) prepreg for a flame-retardant low-transparency thermoplastic continuous fiber strip and a preparation method for the PP prepreg. The PP prepreg is characterized by comprising the following components in parts by weight: 40 to 80 parts of high melt index block co-polymerized polypropylene, 8 to 20 parts of high melt index random copolymer polypropylene, 1 to 5 parts of ethylene-vinyl acetate copolymer, 2 to 10 parts of polypropylene grafted maleic anhydride, 6.5 to 15 parts of halogen-free flame retardant PP masterbatch, 1 to 3 parts of cooling masterbatch, 0.01 to 0.1 part of antioxidant, 1 to 3 parts of sunscreen, and 0.5 to 4 parts of scratch resistant agent. By adopting the PP (Propene Polymer) prepreg for the flame-retardant low-transparency thermoplastic continuous fiber strip and the preparation method for the PP prepreg, the thermoplastic resin PP is modified, the problems about the fluidity of matrix resin and the infiltrating effect are solved, and simultaneously, the material is endowed with high environment-friendly and flame-retardant characteristics. The preparation method is simple in process, low in production energy consumption and high in practical value, and has a great practical value.