The purpose of this paper is to present new approach in automatic tool path generation in contour milling based on genetic algorithm and bitmap representation of work piece and additional resources. It deals with the problem of tool path generation and optimization in contour milling which is the most common case in metalworking industry. The starting point is assumption that the geometry of initial working piece, machined part and clamping fixtures is represented as bitmaps, then the mathematical model is presented and genetic algorithm is used to generate and optimize tool path. Proposed approach greatly reduced the costs of part production through improved machining efficiency, realized through independent software solution implemented in object-oriented language Delphi and can be used as starting point for fully autonomous NC code generation.