High-altitude balloon provides a reliable low-cost platform for high altitude scientific experiments. The shape of the balloon is directly adopted as natural-shape or based on natural-shape； however, how to simply and quickly solve the natural-shape equation general-purpose is a difficult problem. The mature solution tool in the field of optimal control—gauss pseudospectral optimization software was used to solve the natural-shape balloon equation which is transformed into the optimal control description. Furthermore, a general algorithm was designed to solve the natural-shape balloon shape with any spherical control factor and any height by analyzing the shape data. Results show that this algorithm can calculate the required natural-shape without adjusting parameters, which is convenient for researchers to quickly obtain a large amount of required spherical data.