The present invention discloses a laser welding device and a laser welding method. The laser welding device is used to weld I-125 seed source titanium tube by laser beam (B), so as to manufacture small closed irradiating source containing titanium tube, setting the I-125 irradiating source in the titanium tube, to implement the laser welding method using the laser welding device. The device comprises holding clamping fixture, for holding the I-125 seed source titanium tube； a rotary clamping fixture, connecting to one side of the holding clamping fixture so as to ensure the holding clamping fixture rotate with prescribed angle； as well as cooling disks, locating on the upper and lower surfaces of the holding clamping fixture.
