A device for resistance spot welding, comprising a pair of electrodes located on a same welding surface of a to-be-welded assembly, the to-be-welded assembly has a symmetry axis, the pair of electrodes are symmetrically arranged on two sides of the symmetry axis, an end of each electrode is provided with a special-shaped contact surface, and each special-shaped contact surface is shifted in a direction away from the symmetry axis relative to an electrode axis; wherein the electrode includes an electrode tip and an electrode rod, an end of the electrode tip is detachably sleeved on an end of the electrode rod, another end of the electrode tip is provided with a boss, and an end surface of the boss is provided with the special-shaped contact surface; characterized in that: the special-shaped contact surface is used for shifting a current density centerline generated by the pair of electrodes in a direction away from the symmetry axis relative to the electrode axis, and/or for deflecting a current density of each electrode in a direction away from the welding surface within the to-be-welded assembly; the special-shaped contact surface comprises a first contact surface, and a second contact surface, wherein a geometric center of the first contact surface is located on a side of the electrode axis distal to the symmetry axis, the second contact surface is connected to a side of the first contact surface proximal to the symmetry axis, and an area of the first contact surface is larger than an area of the second contact surface. the to-be-welded assembly has a symmetry axis, the pair of electrodes are symmetrically arranged on two sides of the symmetry axis, an end of each electrode is provided with a special-shaped contact surface, and each special-shaped contact surface is shifted in a direction away from the symmetry axis relative to an electrode axis; wherein the electrode includes an electrode tip and an electrode rod, an end of the electrode tip is detachably sleeved on an end of the electrode rod, another end of the electrode tip is provided with a boss, and an end surface of the boss is provided with the special-shaped contact surface; characterized in that: the special-shaped contact surface is used for shifting a current density centerline generated by the pair of electrodes in a direction away from the symmetry axis relative to the electrode axis, and/or for deflecting a current density of each electrode in a direction away from the welding surface within the to-be-welded assembly; the special-shaped contact surface comprises a first contact surface, and a second contact surface, wherein a geometric center of the first contact surface is located on a side of the electrode axis distal to the symmetry axis, the second contact surface is connected to a side of the first contact surface proximal to the symmetry axis, and an area of the first contact surface is larger than an area of the second contact surface. the special-shaped contact surface is used for shifting a current density centerline generated by the pair of electrodes in a direction away from the symmetry axis relative to the electrode axis, and/or for deflecting a current density of each electrode in a direction away from the welding surface within the to-be-welded assembly; the special-shaped contact surface comprises a first contact surface, and a second contact surface, wherein a geometric center of the first contact surface is located on a side of the electrode axis distal to the symmetry axis, the second contact surface is connected to a side of the first contact surface proximal to the symmetry axis, and an area of the first contact surface is larger than an area of the second contact surface.