Abstract: The trigonometric function method is usually used to transform the guidance command from Cartesian coordinates into polar coordinates on non-circular cross section missile, but it is easy to cause roll angle command singularity. Based on the theory of generation and conversion of guidance command, the basic cause of generating control singularity was analyzed with the measures of partial differential coefficient and contour line. A strategy to control singularity of roll angle command was presented by partitioning different control areas. In the singularity control area, the smooth control command was adopted to avoid the occurrence of singularity. The result shows that the strategy could greatly eliminate the influence of control singularity of bank-to-turn on the control precision. Simulation results show that this method is reasonable and could be used in engineering.