In the times of mass customization mode, enterprises face more changeable market demand. The traditional product platform can not meet the needs of all customer, therefore the flexible product platform is particularly important. But the method of parametric design is needed to make product platform to be changed rapidly based on flexible product platform. This paper connects parametric design and flexible product platform , and a design process based on flexible product platform with parametric design is developed. Finally the process is applied to the design of belt conveyor, and the flexible product platform with parametric design is set up.