Abstract: A variety of formulas are designed to prepare sprayable epoxy constrained layer coatings. The effects of epoxy resin and curing agent types and the types and dosages of reactive diluents and flame retardants on the bending modulus, viscosity and fire resistance of the constraining layers are investigated. The results show that with the formula of hydantoin epoxy resin HY070 compounding 128 epoxy resin, the phenalkamine curing agent T31 compounding cardanol modified phenalkamine 1102, benzyl glycidyl ether 692 as the active diluents and aluminum hydroxide as the flame retardant, the constrained layer has the best overall performance. The composite loss factor is tested by combining the obtained constrained layer and the existing damping layer, and the result shows that the composite loss factor of the overall temperature domain rises.