The invention provides a waterproof flame-retardant paper cone, a speaker and a preparation method of the paper cone. The waterproof flame-retardant paper cone is composed of pulp, the front surface of the waterproof flame-retardant paper cone contains a waterproof agent, and the back surface of the paper cone contains a flame retardant. According to the waterproof flame-retardant paper cone provided by the invention, the suitable pulp is selected, so that acoustic performance and tone of the paper cone are ensured; at the same time, the paper cone is subjected to waterproof treatment and flame-retardant treatment, the front surface of the paper cone is coated with the waterproof agent, the back surface is coated with the flame retardant, so that the usage amount of the flame retardant andthe waterproof agent can be reduced, the weight increment of the paper cone can be effectively controlled within 5% without affecting the paper pulp composition of the paper cone, the problem that effects are affected because a mutual reaction exists when the flame retardant and the waterproof agent are mixed for use is avoided, the flame retardant grade can reach V-0, the waterproof grade can reach IPX-7, and the flame-retardant waterproof effects are excellent; and the paper cone has good effects when used in the speaker, and has wide market prospects.