A multi-voltage level direct current grid system and a control protection method, the direct current grid system comprising: at least two direct current buses; at least one direct current transformer, one end of which is connected to a first direct current bus while another end is connected to a second direct current bus or a lead-out wire, which may achieve direct current voltage conversion; and at least one lead-out wire current limiter, one end of the lead-out wire current limiter being connected to the second direct current bus while another end is connected to the lead-out wire; the lead-out wire current limiter comprises a first current-limiting unit, and the first current limiting unit comprises a group of direct current switches, as well as a first bypass switch and a first current-limiting resistor unit that are connected in parallel.