The invention relates to the technical field of textile yarns, in particular to a preparation method of roved fine-needle wool knitting yarns. The invention aims at providing a preparation method of the roved fine-needle wool knitting yarns which are light, thin, reduced in cost, thick and soft. The preparation method comprise the following steps: firstly, selecting raw materials: the raw materials comprise 85 to 95 percent of 80S mercerized Australasian wool and 5 to 15 percent of polyester filaments, and the total mixture ratio of the 80S mercerized Australasian wool and the polyester filaments is 100 percent; secondly, preparing pure wool single yarns: carrying out dyeing, uniform mixing of wool, carding, spinning and spooling on 85 to 95 percent of 80S mercerized Australasian wool to obtain 26Nm pure wool single yarns and the like. According to the roved fine-needle wool knitting yarns prepared with the preparation method of the roved fine-needle wool knitting yarns, the outer parts of the polyester filaments are coated with the pure wool single yarns, so that the hand feeling of the pure wool single yarns is similar to that of a pure wool fabric; the polyester filaments are inside, so that the service performance of a product can be improved, and the cost is reduced.