In order to improve the low mechanical properties and cracking of the welded joint between ductile iron and low carbon steel, laser welding was used to weld ductile iron and low carbon steel, and the effects of process parameters on the microstructure and properties of the welded joint were studied. The results show that with the increase of laser power or the gradual slowing of welding speed, the tensile strength of the test piece shows a trend of first increasing and then decreasing. When the welding process parameters are at 4250 W welding power and 2.4 m/min welding speed, the strength of the welded joint of the specimen is at the extreme value of 400 MPa.Three kinds of shell structures (double shell structure, single shell structure, and coreless structure) are formed in the heat-affected zone at the side of nodular cast iron. The microstructure in the weld zone is mainly composed of dendrite, a small amount of martensite, and ledeburite. There are microcracks in the weld zone. The crack-free weld can be obtained by adding nickel-based materials, and the tensile strength can be improved by about 40 MPa, reaching 95% of the base metal. This research is helpful in the optimization of the high-power laser welding process between nodular cast iron and low carbon steel.