Abstract: In view of the broadband oscillation problem caused by the grid-connection of large-scale photovoltaic-thermal bundled integration system via traditional high voltage direct current（LCC-HVDC）transmission system,firstly,the state-space model and impedance model are established in this paper. The results show. that the simplified thermal power model cannot reflect the interaction mode between photovoltaic-thermal bundled integration and LCC-HVDC. Therefore,a six-order detailed thermal power model must be adopted,and then the possible oscillation frequency of the system was calculatedby eigenvalue method. Secondly,impedance method is used to analyze the broadband oscillation,interaction mechanism of the system and the influence of parameter change on the oscillation mode of the system. Finally,PSCAD/EMTDC platform was used to verify the mechanism of broadband oscillation and the effect of the influencing factors. The results show that the broadband oscillation is caused by the negative damping characteristics of the system in some frequency bands. The change of element parameters will change the amplitude of broadband oscillation by affecting the damping of the system. Furthermore,the reasonable parameter range of filter and converter is obtained.