The invention provides a device and a method for tracing cracks of a rock sample. The device comprises a tracer and a support platform, wherein the tracer comprises a transparent container with the Y-coordinate and the X-coordinate, the support platform is connected with the transparent container by bearings, and the transparent container can rotate relative to the support platform. The method comprises the following steps of installing the rock sample, tracing points, and imaging; or installing the rock sample, scanning and carrying out image processing. The device for tracing the cracks of the rock sample has the advantages of simpleness in manufacturing, high precision, convenience in operation and maintenance, and realization in programmed tracing; the method for tracing the cracks of the rock sample has the advantages of high working efficiency and convenience.