The invention provides a method and device for predicting a drilling risk. The method includes the steps of obtaining two-dimensional coordinate values of center points of all drilled wells in the horizontal plane within a reservoir to be evaluated, and acquiring a plurality of first gamma values of the drilled wells at a plurality of preset depths, with the depth difference between the adjacent preset depths being equal; normalizing the first gamma values of each drilled well to obtain second gamma values in a one-to-one correspondence with the first gamma values of the drilled well; obtaining second gamma values of an undrilled unit area in the reservoir at the plurality of preset depths according to the second gamma values of the drilled wells, the preset depths corresponding to the second gamma values, the two-dimensional coordinate values of the drilled wells, and two-dimensional coordinate values and pre-set depths of the un-drilled unit area in the reservoir; calculating the sandstone development probability in the unit area; and determining the drilling risk in the unit area based on the sandstone development probability. According to the method and device provided by the invention, the accuracy of the predicted drilling risk in the un-drilled area in the reservoir is high.