Polymer sulfonate fire retardant, and preparation method as well as application thereof

The invention relates to a polymer sulfonate fire retardant, containing a copolymer obtained by polymerization reaction from an unsaturated sodium sulfonate monomer, an unsaturated potassium sulfonate monomer and a vinyl monomer; the vinyl monomer is selected from any one or more of C6-C12 aromatic vinyl compounds, a (methyl) acrylate compound, a vinyl amide compound, a vinyl ether compound or a cyanation vinyl ether compound; the mole ratio of the total of the unsaturated sodium sulfonate monomer and the unsaturated potassium sulfonate monomer to the vinyl monomer in polymer sulfonate is (0.025 to 0.5):1; the mole ratio of the unsaturated sodium sulfonate monomer to the unsaturated potassium sulfonate monomer in the polymer sulfonate is (30:70) to (90:10); a number-average molar mass of the polymer sulfonate is 1000-200000. The invention also relates to a preparation method and application of the polymer sulfonate fire retardant.