In this paper the hybrid method of manufacturing knowledge representation in the CAPP knowledge based system is presented. In the presented solution the manufacturing knowledge as well as the product design is represented by means of the object method. This paper shows only results obtained at the object design stage (OOD). Currently the scope of decision problems solved by proposed system is limited to axi8211;symmetric products, but basis on the achievements to date it is thought to develop this system in order to widen the subjected products group. Moreover the detailed description of the inference engine of the CAPP system is given. In the inference engine the two groups of rules were distinguished. In the paper content the examples for each group of rules are shown.