The utility model discloses an instrument for tunnel excavation during tunnel model is experimental utilizes circular scale, but the preparation of members such as telescopic rod and blade, circular scale superscript has the angle scope of angle scale, control excavation line, but telescopic rod control tunnel excavation depth can be selected according to the model size, the blade is used for cutting country rock simulant material. The utility model has the advantages of: can be to common tunnel section shape, the model of various geometric similarity ratio excavates, has simple structure, convenient operation, the adjustable range is big, and the experimental excavation method of tunnel model has been standardized to application scope advantage such as wide, can effectively improve modeltest's work efficiency.