Abstract: The pilot branch of the single inductance dual output (SIDO) Buck-Boost converter contains a right half plane zero point, which belongs to a non minimum phase system. Therefore, its stability needs to be analyzed. Firstly, the state space averaging method was used to establish the system Jacobian matrix, and the Routh Hurwitz stability criterion and eigenvalue change trend graph were used to analyze the stable range values of the proportional and integral coefficients of single and double branches. Then, based on the root trajectory curve, it is determined that the dual branch output mode is a subset of the single branch output mode.