Valve short-circuit protection is the primary protection for high voltage direct current（HVDC） converters. The fault current is analyzed and calculated when the valve short-circuit faults happen at rectifier side and inverter side respectively. The result shows that the fault current in case of inverter side failure is much less than that of rectifier side. Based on it， the operation equation for valve short-circuit protection is analyzed. It is disclosed that the valve short-circuit protection for the inverter side may fail to trip due to the comparatively little fault current and the impacts on the control system. On the other hand， due to the impacts of current transformer saturation and the difference between the transient characteristics for current transformer of each phase， the protection may mal-operate during unloaded converter transformer energized. The theoretical analysis is verified by numerous simulation tests with real time digital simulator（RTDS）. The short-circuit protection configuration and setting suggestions are proposed to coordinate the contradiction between selectivity and sensitivity.