The antifloating anchors have been widely used in the antifloating problem of underground engineering recently. Due to the complexity of the anchor force in the geotechnical material and the limitations of traditional monitoring methods, it is impossible to grasp the deformation characteristics of the anchor comprehensively. The pullout test of the antifloating anchor on-site is carried out in this paper based on the housing construction project. The Optical Frequency Domain Reflectometry (OFDR) technology is used, the strain distributions are obtained, and the distribution law of axial force is analyzed. The test results show that the strain of the antifloating anchor gradually decreases when anchoring depth increases and eventually tends to zero. The anchoring section is divided into main stressed section and unstressed section. The results show that the OFDR technology can be used to effectively monitor the antifloating anchor in the pullout test; it will help to grasp the deformation of antifloating anchor.