The invention discloses a dynamic voltage source control-based direct-current grounding searching method and apparatus. The method comprises the following steps that: step one, the voltage amplitude +U1 of a positive pole busbar and the voltage amplitude -U2 of a negative pole busbar are detected, and sum value voltage U is obtained; step two, if the absolute value of the ratio of the voltage amplitude +U1 of the positive pole busbar to the sum value voltage U is smaller than a threshold value K, the positive pole busbar is grounded; if the absolute value of the ratio of the voltage amplitude -U2 of the negative pole busbar to the sum value voltage U is smaller than the threshold value K, the negative pole busbar is grounded; step three, dynamic detection voltage is applied to grounded busbars, wherein the dynamic detection voltage is detection voltage which is adjusted and outputted by a dynamic voltage source by following the real-time voltage of a direct-current system; and step four, the grounding resistance of branch circuits corresponding to the grounded busbars is detected, and after a branch circuit with ultra-high resistance is determined, the applying of the dynamic detection voltage is stopped. According to the dynamic voltage source control-based direct-current grounding searching method and apparatus, dynamic voltage source control is adopted, and therefore, it can be ensured that the amplitude of applied signals and measurement sensitivity are maximum, and the misoperation of a relay and protection caused by a situation that the voltage to earth of the busbars of the direct-current system exceeds a dangerous value can be effectively avoided.