The invention discloses a method and a device for realizing lateral drilling of a blind hole in a small-diameter deep hole. The method comprises the following steps: (1) a rock is taken, and an end surface thereof is flatly cut for drilling; (2) the center of the hole serves as an origin of coordinates, and a coordinate axis is built by a painting pen; (3) water or cooling oil is fully filled in the hole; (4) the lateral drilling is performed by a drilling machine; and (5) azimuth angles of the drilling are recorded through the coordinate axis, the drilling depth is recorded through a dividing ruler on a drill rod, and the drilling operation is finished. A drilling machine part is connected with a drilling machine clamping nozzle through a bearing; the drilling machine clamping nozzle clamps the drill rod through a clamping nozzle; a drilling machine rotating shaft is respectively connected with a drilling machine chuck and a drilling machine; the drilling machine clamping nozzle is respectively connected with the drilling machine chuck and the drill rod; the drill rod and a drill rod protective cover are fixed by screws through fixtures; the tail end of the drill rod is connected with the drilling machine rotating shaft; and the other end of the drill rod is connected with a transmission device. The method has the advantages of feasibility, simple operation, precise drilling, wide application range and easy realization of batch drilling. The device has good safety performance.