Hill stability of deep-sea steel catenary riser (SCR) was predicted based on bi-frequency excitation. The SCR was transferred into top tensioned riser (TTR) based on Vandiver theory, the multi-frequency signal is proposed to simulate the stochastic tension fluctuation, and Hill equation was obtained according to the dynamic motion equation of TTR under multi-frequency excitation. The parametric stability characteristic of the SCR system under bi-frequency excitation, a typical case of multi-frequency, was primarily discussed, and bi-frequency excitation was used for practical engineering analysis. The results show that multi-frequency excitation can better predict real sea condition than single frequency, the prediction of real external excitation is vital to the parametric stability prediction of SCR, and the riser safety design requirements are determined by the corresponding form of excitation function chosen.