The invention belongs to the technical field of oil exploration and development, and relates to a rock drillability evaluation method based on rock debris nanoindentation, which comprises the following steps: carrying out nanoindentation test on a rock debris sample, collecting a displacement load curve of an indenter, and calculating the microhardness of the nanoindentation test; calculating the mineral composition of the rock debris according to the statistical distribution characteristics of the microhardness, and converting the microhardness of the rock debris nanoindentation test into macroscopic indentation hardness; and according to the relevance between the macroscopic indentation hardness of the rock and the drillability grade value of the rock, establishing the drillability grade value of the rock, which is represented by the microhardness of the rock debris nanoindentation test. Under the conditions that the number of underground rock samples is small and the cost is high, the method breaks through the limitation of a conventional test on the size and shape of the sample, solves the problem of testing the mechanical parameters of deep rocks in the field of oil and gas drilling, is a powerful supplement to a conventional test method, and provides a basic support for optimizing a drill bit and improving the drilling speed.