In this paper, a tool path generation and optimisation method for the single point incremental forming (SPIF) is developed. Two important issues in SPIF: the surface smoothness and dimensional inaccuracy are considered. In the work, a direct relationship between the step depth and scallop height is established. Started with an initial design represented by a B-spline surface, a helical tool path is generated based on the calculated slice height. To minimise the geometrical inaccuracy from global and local springback, FE analysis is implemented and the geometrical errors are quantified. Then the B-spline surface is updated with consideration of the predicted geometrical errors and a new tool path is generated based on the updated surface. This operation is repeated iteratively until the geometrical error reduces to the specified tolerance. Two case problems including a truncated pyramid shape and cranial plate for medical applications are evaluated using this approach. The results suggest that the proposed tool path generation method is an effective method for increasing the geometrical accuracy for complex SPIF formed parts.