The invention discloses a recoverable measuring device for monitoring internal displacement of tunnel surrounding rocks and a method of the recoverable measuring device. The recoverable measuring device includes a protective casing which is arranged in surrounding rock bodies in a measuring direction and is a rigid body, and a plurality of opening parts arranged in a vertical direction are formedin the lateral wall of the protective casing in different depth; a plurality of measuring point devices relatively move in a vertical direction of the protective casing, and the measuring point devices include measuring point occurrence bodies, a connection part and a measuring point fixing device; the measuring point occurrence bodies are arranged on the external side of the protective casing, the measuring point occurrence bodies are fixedly connected with the surrounding rocks by grouting bodies, the measuring point occurrence bodies are connected with the measuring point fixing device arranged on the internal side of the protective casing by the connection part, and the connection part penetrates though the opening parts; and a displacement measurement device is fixedly arranged in theprotective casing, the displacement measurement device is used for measuring the relative displacement between the measuring point fixing device and the protective casing.