In view of the fact that the ship-to-land cruise missile's flight path needs to refer to the approximate geodesic route， the calculation method of geodesic distance between two points in space， which is easy to program and has improved accuracy， is put forward on the basis of fully considering the planning process of the missile's path from sea to land. Based on the calculation of the parameters of the earth ellipsoid model considering the altitude， the calculation formula of space waypoint considering the altitude is re-derived by using the Bowring inverse solution formula. The relevant calculation examples show that this method can improve the accuracy of distance calculation and is easy to be implemented in engineering.