A micro-channel heat exchanger, comprising: a plurality of flat tubes, wherein a width of each of the plurality of flat tubes is A, a thickness of the each of the plurality of flat tubes is T, the each of the plurality of flat tubes comprises a bent section and two straight sections, end portions of the two straight sections are communicated with two ends of the bent section respectively, the bent section has an outer bent surface and an inner bent surface along a thickness direction of the bent section, and the two straight sections are symmetrically arranged relative to a symmetry plane; a first collector tube, end portions of straight sections, on one side of the symmetry plane, of the plurality of flat tubes being communicated with the first collector tube; and a second collector tube, end portions of straight sections, on the other side of the symmetry plane, of the plurality of flat tubes being communicated with the second collector tube; wherein the plurality of flat tubes are arranged in parallel along a first direction, a distance between straight sections of two adjacent flat tubes in the plurality of flat tubes is B, and the first direction is parallel to the symmetry plane; wherein the bent section is formed by bending around an axis with a predetermined radius R1, both the first collector tube and the second collector tube extend in the first direction, a radius of an outer circumference of the first collector tube is R2, and a radius of an outer circumference of the second collector tube is R3, R3≦R2≦R1≦2R2+A; wherein the bent section is formed by bending around an axis with the predetermined radius R1, characterised in that a length direction of a projection of each of the straight sections on the symmetry plane is a height direction, and a distance between a highest point of the outer bent surface and a lowest point of the inner bent surface along the height direction on the symmetry plane is H1, wherein T < H 1 ⩽ A / B + 1 × T; and a distance between the highest point of the outer bent surface and the lowest point of the bent section in the height direction is H, T + R 1 ⩽ H ⩽ A / B + 1 × T + 1.2 R 1 + 2 A. a plurality of flat tubes, wherein a width of each of the plurality of flat tubes is A, a thickness of the each of the plurality of flat tubes is T, the each of the plurality of flat tubes comprises a bent section and two straight sections, end portions of the two straight sections are communicated with two ends of the bent section respectively, the bent section has an outer bent surface and an inner bent surface along a thickness direction of the bent section, and the two straight sections are symmetrically arranged relative to a symmetry plane; a first collector tube, end portions of straight sections, on one side of the symmetry plane, of the plurality of flat tubes being communicated with the first collector tube; and a second collector tube, end portions of straight sections, on the other side of the symmetry plane, of the plurality of flat tubes being communicated with the second collector tube; wherein the plurality of flat tubes are arranged in parallel along a first direction, a distance between straight sections of two adjacent flat tubes in the plurality of flat tubes is B, and the first direction is parallel to the symmetry plane; wherein the bent section is formed by bending around an axis with a predetermined radius R1, both the first collector tube and the second collector tube extend in the first direction, a radius of an outer circumference of the first collector tube is R2, and a radius of an outer circumference of the second collector tube is R3, R3≦R2≦R1≦2R2+A; wherein the bent section is formed by bending around an axis with the predetermined radius R1, characterised in that a length direction of a projection of each of the straight sections on the symmetry plane is a height direction, and a distance between a highest point of the outer bent surface and a lowest point of the inner bent surface along the height direction on the symmetry plane is H1, wherein T < H 1 ⩽ A / B + 1 × T; and a distance between the highest point of the outer bent surface and the lowest point of the bent section in the height direction is H, T + R 1 ⩽ H ⩽ A / B + 1 × T + 1.2 R 1 + 2 A.