Compared with full-bridge modular multilevel converter (MMC),the hybrid MMC composed of half bridge sub-module and full bridge sub-module has the low cost and high DC fault ride-through capability. The DC fault transient analysis is the basis of device selection and proportioning design of hybrid MMC. In order to analyze the transient characteristics of hybrid MMC after DC side fault, the equivalent fault models of DC pole-pole short circuit during the non-blocking DC fault ride-through in rated operation and step-down operation are established. The dynamic switching process of each bridge arm sub-module of hybrid MMC during DC fault ride-through is analyzed. The transient process before the switching of the non-blocking DC fault ride-through control strategy is equivalent to the uncontrollable sub-module capacitor discharge process,while the transient process after switching the control strategy is equivalent to the current limiting process with the initial energy storage of the inductor and the reverse voltage source. The analytical calculation method of the short-circuit current on the DC side of hybrid MMC is also given in this paper. Finally,the effectiveness of the model and calculation method proposed in this paper is verified by the PSCAD/EMTDC simulation platform,which can provide a reference for the optimal design of hybrid MMC.