The invention relates to a phosphorous ion-free treating agent for treating a steel plate. The technical scheme is that: the phosphorous ion-free treating agent comprises the following components in percentage by weight: 1 to 5 percent of inorganic phase, 1 to 5 percent of organic phase and the balance of water, wherein the inorganic phase consists of 5 to 20 percent of fluorozirconic acid, 2.5 to 10 percent of hydrofluotitanic acid, 2 to 4 percent of magnesium nitrate, 1 to 3 percent of aluminum nitrate, 0.1 to 1 percent of ferric nitrate, 0.1 to 1 percent of ammonium nitrate, 0.1 to 1 percent of tetrabutyl titanate, 0.01 to 0.5 percent of hexamethylene tetramine and the balance of water; and the organic phase consists of 20 to 25 percent of silane coupling agent, 10 to 20 percent of ethanolamine, 5 to 10 percent of nonylphenol polyoxyethylene ether and the balance of water. When the phosphorous ion-free treating agent is used for treating a metal work piece, such as the steel plate, the formed film layer has high corrosion resistance, adhesive forces of a metal substrate and a coating are enhanced, the service life of 5 percent neutral salt spray is longer than 1,000 hours, and the coating performance reaches or exceeds that of a ternary zinc phosphorization treatment process.