This work lays a foundation for promoting the application of incoherent spatial combining laser in laser surface heat treatment with high speed and flexible processing. 18 semiconductor laser beams at 972 nm output by the fiber were arranged in parallel according to the "matrix". By implementing beam collimation and incoherent spatial beam combination, a 10 kW combined laser beam with rectangular spot characteristics was obtained. The radius of the collimated laser beam, the distance between adjacent laser beams and the overlapping rate of the combined laser were theoretically analyzed, respectively. The structural model of the beam combiner was built using Code V software, and the spot energy distribution of the combined laser was simulated using TracePro software. Based on the above work, a 10 kW 18×1 incoherent spatial laser combiner of outputting a rectangular spot was developed. Within the combined length of 200 mm, the combined laser beam had a single rectangular spot shape. A beam combining power of 10.249 kW was achieved with a focal spot diameter of 31 mm×11 mm, a center wavelength of 972.34 nm and a linewidth of 2.27 nm.