Abstract: As LCC-HVDC technology is widely used in the long-distance power transmission, it is of great significance to analyze the stability of the LCC-HVDC technology under the small disturbances. In view of the inevitable commutation phenomenon in the process of AC-DC conversion of the LCC-HVDC, the description and treatment of the commutation overlap process is the key to realize the accurate modeling of the power grid commutation converter. In practical engineering application, the RC damping circuit is generally connected in parallel at both ends of the converter valve to suppress the transient overvoltage and thehigh voltage change rate. At present, there is seldom literature on the studies of the influence of damping circuit on converter modeling. Firstly, considering the damping circuit of the converter valve, the commutation process of the converter is analyzed and discussed, and the transfer function between the variables of the converter is established; Then, in order to illustrate the accuracy of the transfer function modeling, the frequency scanning is carried out on the PSCAD/EMTDC platform; Finally, the AC admittance model is established and the stability of the DC transmission system is simply analyzed and verified.