For the phenomenon of low frequency oscillation in the AC-DC interconnected system which contains VSC-HVDC, a method based on H∞ loop shaping is proposed to design the additional robust damping controller. The reduced order model of the system and the related oscillation frequency are identified by total least squares-estimation on signal parameters via rotational invariance techniques. The robust damping controller is designed for the reduced order model of the system based on H∞ loop shaping and normalized coprime factorization. Finally, a simulation created in PSCAD/EMTDC which is a four-machine two-area system with a VSC-HVDC link. The results show that the robust damping controller designed for VSC-HVDC can well suppress the low frequency oscillation of the system in different disturbances. The controller shows good control performance and strong robustness; furthermore, output feedback control is utilized in the design of the controller, being convenient for practical application. This work is supported by Science and Technology Project of State Grid Corporation of China (No. SGQHJY00GHJS1400044).