The utility model discloses a rectangular spline hob assembly. The rectangular spline hob assembly comprises a rectangular spline hob and a hob cushion sleeve. The hob cushion sleeve is installed at one end of the rectangular spline hob and a spline hob shaft is sleeved with the hob cushion sleeve and the rectangular spline hob. The rectangular spline hob comprises a hob body. An axial hole is formed in the center of the hob body. Multiple chipping teeth are arranged on the peripheral wall of the hob body. Chip grooves are formed between two adjacent chipping teeth. Each chipping tooth is composed of a main chipping tooth and an auxiliary chipping tooth. According to the rectangular spline hob assembly, the hob cushion sleeve is used for adjusting relative positions of the rectangular spline hob and a spline shaft blank to be machined. Each chipping tooth of the rectangular spline hob is detached into the main chipping tooth and the auxiliary chipping tooth. The rectangular spline hob assembly has the advantages of improving the utilization efficiency of the rectangular spline hob and reducing the replacement frequency of the hob.