Disclosed is a current sampling circuit including a proportional current output circuit and a full differential common mode negative feedback circuit, specifically the proportional current output circuit is configured to calculate a current output from a power device according to a preset proportion to obtain a first proportional current and a second proportional current, and to output the first proportional current and the second proportional current to the full differential common mode negative feedback circuit; and the full differential common mode negative feedback circuit is configured to shunt respectively the first proportional current and the second proportional current using a full differential common mode negative feedback network with a bias current in microamps to obtain a first sampling current and a second sampling current, and to output constantly the first sampling current and the second sampling current. Further disclosed is a current sampling method.