The invention relates to a hydrophobic composite steel core glass fiber anti-floating anchor. An anchor body is overall cylindrical and is composed of a fiber resin layer and a steel strand wrapped in the fiber resin layer; threads are arranged at the two ends of the anchor body; the middle of the anchor body is a smooth surface and coated with a hydrophobic membrane. The hydrophobic composite steel core glass fiber anti-floating anchor overcomes the defects in the prior anti-floating art, the end of the anti-floating anchor is provided with a self-anchoring device, an acting point of the anti-floating anchor is formed, the outer surface of the anti-floating anchor is coated with the hydrophobic membrane except for the anchoring section, and therefore weak binding power is formed between the outer circumferential surface of the anchor and cement paste, the construction process is simplified, the construction speed is increased, and the construction quality is improved.