The invention discloses a method and a system for acquiring fault measures of direct current unipolar line of a flexible direct current power grid, and belongs to the technical field of safe and stable control of the power system. The method of the invention comprises the following steps of: determining the topology structure of the flexible direct current power grid safety control system; acquiring a calculation data of the fault measure quantities of the safety control system of the flexible direct current power grid according to the topological structure; defining a calculation variable ofthe fault measure quantities of the flexible direct current power grid security system according to the converter lockup fault; and acquiring the fault measure quantities according to the calculationdata and the calculation variables. According to the method and system for acquiring fault measures of direct current unipolar line of a flexible direct current power grid, the safety control system can calculate the correct fault measure quantities in the event of converter lockup fault, and the safe and stable operation of the flexible direct current power grid can be guaranteed effectively.