A laser welding apparatus comprising a single-core optical fiber and a barrel configured for beam shaping and converging of emergent light from the single-core optical fiber in order to realize combined welding of a high power density spot (20, 100) and a lower power density spot (21, 33, 45, 53, 92, 101), the laser welding apparatus being characterized in that: in an interior of the barrel, a cylindrical lens (10, 30, 80, 90), a collimation lens, and a condensing lens are sequentially arranged on a same optical axis as the single-core optical fiber, the cylindrical lens being arranged in the interior of the barrel and located between an output of the optical fiber and the collimation lens, the cylindrical lens having a focal distance that is longer than that of the condensing lens, a hollowed portion (15, 82) of the cylindrical lens being arranged in a light beam emerging from the optical fiber; or wherein, in an interior of the barrel, a collimation lens, a cylindrical lens (40, 50, 80, 90), and a condensing lens are sequentially arranged on a same optical axis as the single-core optical fiber, the cylindrical lens being arranged in the interior of the barrel and located between the collimation lens and the condensing lens, the cylindrical lens having a focal distance that is longer than that of the condensing lens, a hollowed portion (41, 82) of the cylindrical lens being arranged in a collimated light beam emerging from the collimation lens; or wherein, in an interior of the barrel, a collimation lens, a condensing lens, and a cylindrical lens (60, 70, 80, 90) are sequentially arranged on a same optical axis as the single-core optical fiber, the cylindrical lens being arranged in the interior of the barrel and located behind the condensing lens, the cylindrical lens having a focal distance that is longer than that of the condensing lens, a hollowed portion (61, 82) of the cylindrical lens being arranged in a focused light beam emerging from the condensing lens; such that the high power density spot is a circular spot having a diameter of 10-200um, and the lower power density spot has a shape that is one of an ellipse, a rectangle, and a strip, and such that the lower power density spot has a length in a range of 100-10000 μm and a width in a range of 10-200 μm; in that the laser welding apparatus is configured to switch cylindrical lenses having different hollowed portions for varying the size of the hollowed portion of the cylindrical lens, so that intensity values of the high power density spot and the lower power density spot can be adjusted; in that the laser welding apparatus further comprises means for moving the cylindrical lens frontwards or rearwards, so that the intensity values of the high power density spot and the lower power density spot can be changed. in an interior of the barrel, a cylindrical lens (10, 30, 80, 90), a collimation lens, and a condensing lens are sequentially arranged on a same optical axis as the single-core optical fiber, the cylindrical lens being arranged in the interior of the barrel and located between an output of the optical fiber and the collimation lens, the cylindrical lens having a focal distance that is longer than that of the condensing lens, a hollowed portion (15, 82) of the cylindrical lens being arranged in a light beam emerging from the optical fiber; or wherein, in an interior of the barrel, a collimation lens, a cylindrical lens (40, 50, 80, 90), and a condensing lens are sequentially arranged on a same optical axis as the single-core optical fiber, the cylindrical lens being arranged in the interior of the barrel and located between the collimation lens and the condensing lens, the cylindrical lens having a focal distance that is longer than that of the condensing lens, a hollowed portion (41, 82) of the cylindrical lens being arranged in a collimated light beam emerging from the collimation lens; or wherein, in an interior of the barrel, a collimation lens, a condensing lens, and a cylindrical lens (60, 70, 80, 90) are sequentially arranged on a same optical axis as the single-core optical fiber, the cylindrical lens being arranged in the interior of the barrel and located behind the condensing lens, the cylindrical lens having a focal distance that is longer than that of the condensing lens, a hollowed portion (61, 82) of the cylindrical lens being arranged in a focused light beam emerging from the condensing lens; such that the high power density spot is a circular spot having a diameter of 10-200um, and the lower power density spot has a shape that is one of an ellipse, a rectangle, and a strip, and such that the lower power density spot has a length in a range of 100-10000 μm and a width in a range of 10-200 μm; in that the laser welding apparatus is configured to switch cylindrical lenses having different hollowed portions for varying the size of the hollowed portion of the cylindrical lens, so that intensity values of the high power density spot and the lower power density spot can be adjusted; in that the laser welding apparatus further comprises means for moving the cylindrical lens frontwards or rearwards, so that the intensity values of the high power density spot and the lower power density spot can be changed.