With the widespread application of line commutated converter based high voltage direct current (LCC-HVDC) technology, the interactive stability problem of AC-DC hybrid power systems is becoming increasingly prominent. This paper first establishes the transfer function model of an LCC converter considering the nonlinear commutation overlapping dynamic process based on the state-space averaging method. To accommodate more complex DC transmission system modeling, it is proposed to establish small-signal models of LCC-HVDC subsystems using a modularization idea, and the interface matrix reflecting the electrical coupling characteristics between AC/DC system and converter is derived to realize subsystem connection, thereby modularly establishing accurate and easily expandable small-signal models of double-ended LCC-HVDC system. These consider the control time delay and phase fluctuation of phase-locked loop output. Finally, the influence of control system parameters and control time delay on the small disturbance stability of the system and the dominant factors of the instability modes are analyzed. The mechanism of AC-DC hybrid resonance of double-ended LCC-HVDC system and the interaction between sender and receiver are revealed. The research results can provide a theoretical basis for the design of system parameters and resonance suppression measures.