Qizong hydropower station was built in a high dam reservoir of canyon area, and the biggest dam was preliminarily planned to be as high as about 358m. The designed hole depth of ZK119 was 350m and located in the underground plant of left bank of upper damsite. Compared to the vertical borehole, the horizontal hole is more difficult in construction technology with higher hidden danger and higher requirements of drill pipe and drilling equipment. The construction point of horizontal excavation is hole deviation control, and taking the example of horizontal hole ZK119, the paper elaborated the horizontal hole drilling technology in the principles of horizontal drilling technology, technical features and the measures of deviation control.