In this research, an effective tool path generation for free form surface is investigated by using 8-axis robot system. Processing freeform surface using this robot is already done, and the way for processing freeform surface and tool path generation using this system is established. However, because of many problems, for example interference on tool and work, complexity of the algorism for tool path generation, and so on, it is difficult to process complex form, and processing is not inefficient. In this research, I consider improving the algorism for tool path generation, and suggest processing efficiently and processing complex form.