Abstract: Provided are a method and system for protecting the HVDC line, device, and storage medium. The method for protecting the HVDC line includes that: a DC line parameter and a DC system operation parameter are acquired, and a DC line protection installation position operation parameter is sampled; a line-mode fault voltage of a sampling point, a zero-mode fault voltage of the sampling point, a line-mode fault current of the sampling point, and a continuous rate of change of the line-mode fault current are calculated; in response to starting the line protection, the line-mode fault voltage is compensated based on the DC line parameter, the DC system operation parameter, and a first peak value of the line-mode fault voltage; and in response to determining that the HVDC line is faulty, a line fault polarity is determined based on the zero-mode fault voltage.