The invention discloses a rock displacement direct-reading instrument, comprising a measurement line, a fixed base, a reading window, a ruler tray, a fixed casing, a tightening spring, a shaft and a wire spool, wherein the fixed casing, the reading window and the fixed base are integrated, the fixed base is arranged at the bottom of the fixed casing, the reading window is arranged at the top of the fixed base, the shaft is fixed in the fixed casing, the tightening spring and the shaft are fixedly connected, the center bore of the ruler tray penetrates through the shaft and are fixedly connected with the tightening spring, the center bore of the wire spool penetrates through the shaft and are in rolling connection with the shaft, the wire spool is connected with the ruler tray, the measurement line are wound on the wire spool. The inventive rock displacement direct-reading instrument has high measurement precision, simple structure, convenient operation, good long-time stability; the invention can conveniently and rapidly read the displacement data of each measurement point, and obtain the actual displacement of the measurement point in a period only by simple conversion.