A kit comprising: a detection instrument; and a biosensor, comprising an insulating base plate, a working electrode and a counter electrode that are positioned on the insulating base plate, at least one of the working electrode and the counter electrode being provided with a reaction reagent layer, the biosensor further comprising an automatic encoding device, the automatic encoding device comprising an electrode system positioned on the insulating base plate, the electrode system comprising a first electrode, a second electrode, and a third electrode; the first electrode, the second electrode, and the third electrode respectively comprising a first contact, a second contact, and a third contact which are electrically connectable with the detection instrument, wherein the first electrode and the second electrode are selectively electrically connected with a first connecting point; the second electrode and the third electrode are selectively electrically connected with a second connecting point; a loop formed by the first contact, the first connecting point, and the second contact corresponds to an electric parameter R1; a loop formed by the second contact, the second connecting point, and the third contact corresponds to an electric parameter R2; a loop formed by the first contact, the first connecting point, the second connecting point, and the third contact corresponds to an electric parameter R3; characterised in that after the automatic encoding device is electrically connected with the detection instrument through the contacts, the detection instrument is configured to determine the resistance of any two of the loops and to determine a code according to one of the following formulas: S 1 = K 1 ∗ R 1 R 2, or S 2 = K 2 ∗ R 3 R 2, or S 3 = K 3 ∗ R 1 R 3, wherein K1, K2, and K3 are correction coefficients, respectively; and wherein the automatic encoding device, and the working electrode and the counter electrode on the biosensor are respectively positioned on two different insulating layers and are bonded together back to back. a detection instrument; and a biosensor, comprising an insulating base plate, a working electrode and a counter electrode that are positioned on the insulating base plate, at least one of the working electrode and the counter electrode being provided with a reaction reagent layer, the biosensor further comprising an automatic encoding device, the automatic encoding device comprising an electrode system positioned on the insulating base plate, the electrode system comprising a first electrode, a second electrode, and a third electrode; the first electrode, the second electrode, and the third electrode respectively comprising a first contact, a second contact, and a third contact which are electrically connectable with the detection instrument, wherein the first electrode and the second electrode are selectively electrically connected with a first connecting point; the second electrode and the third electrode are selectively electrically connected with a second connecting point; a loop formed by the first contact, the first connecting point, and the second contact corresponds to an electric parameter R1; a loop formed by the second contact, the second connecting point, and the third contact corresponds to an electric parameter R2; a loop formed by the first contact, the first connecting point, the second connecting point, and the third contact corresponds to an electric parameter R3; characterised in that after the automatic encoding device is electrically connected with the detection instrument through the contacts, the detection instrument is configured to determine the resistance of any two of the loops and to determine a code according to one of the following formulas: S 1 = K 1 ∗ R 1 R 2, or S 2 = K 2 ∗ R 3 R 2, or S 3 = K 3 ∗ R 1 R 3, wherein K1, K2, and K3 are correction coefficients, respectively; and wherein the automatic encoding device, and the working electrode and the counter electrode on the biosensor are respectively positioned on two different insulating layers and are bonded together back to back.