The invention provides a method for preventing rock burst of a nearly-upright coal seam by deep and shallow hole relaxation blasting, and belongs to the technical field of prevention of rock burst disasters. The method comprises the steps that firstly, a stress concentration zone is determined according to monitoring data; then, multiple rows of deep blasting holes and shallow blasting holes are alternately formed in top and bottom plates of the area to be subjected to pressure relief, two deep blasting holes are formed in each row, three shallow blasting holes are formed in each row, the rowspacing is 20m, the direction of the blasting holes is distributed in the shape of a fan, and the depth of the blasting holes can at least reach a peak value area of the bearing pressure; after drilling is completed, charging is carried out, a leading wire is connected, hole sealing is carried out, positive manual charging is adopted, loess is used for blocking, and the wire connection method adopts parallel connection in the holes and series connection between the holes; and finally, blasting is performed by a blasting machine, the blasting method adopts a single-time single-row mode, the advanced blasting distance of the deep blasting holes is controlled between 30m and 90m, and the shallow blasting holes follow the working face for promoting blasting. The method for preventing the rockburst of the nearly-upright coal seam by deep and shallow hole relaxation blasting can significantly reduce the stress concentration of the working face, can weaken the risk of the rock burst of the working face, and is suitable for steeply-inclined and nearly-upright coal seams.