The invention discloses a deep deformation monitoring device with an appearance deformation measuring function. The deep deformation monitoring device comprises a benchmark measuring rod and a relative-deformation measuring rod, wherein the benchmark measuring rod is longer than the relative-deformation measuring rod, and the two ends of each of the benchmark measuring rod and the relative-deformation measuring rod are provided with an anchoring rod and a fixing seat respectively. One side of each fixing seat is provided with an inserting hole, and the other side of each fixing seat is provided with a sensor. The benchmark measuring rod and the relative-deformation measuring rod are connected with the sensors. The other end of each sensor is connected with a detecting device through a cable, and the other side of each fixing seat is provided with a protective sleeve. The cables penetrate through the protective sleeves, the side walls of the protective sleeves are provided with forced centering bases, the outer end faces of the forced centering bases are connected with an observation prism through a connector, and prism leveling devices are arranged between the observation prism and the forced centering bases. According to the deep deformation monitoring device, monitoring data of appearance deformation and monitoring data of deep deformation are collected synchronously, the maximum deformation depth of a monitored project can be effectively determined, the monitoring process is convenient and fast to conduct, and the deep deformation monitoring device can be widely applied to the field of safety monitoring.