The invention discloses a preparation method for an elastic fabric. 60-70% of 70S wool and 30-40% of Sorona fiber are used to prepare the new elastic fabric though the processes of dyeing, spinning, weaving and finishing. The product is the elastic environment-friendly new fabric, is prepared by blending wool and Sorona fiber, has the characteristics of being waxy and smooth in wool and full in elasticity, is comfortable to wear and not uptight. Due to the addition of Sorona fiber, the original properties of the raw materials are reserved, the quality of wool is reflected, the softness and skin-touch are improved, the drapability and the fabric luster are improved, and the fabric is endowed with natural soft feeling, replaces polyurethane, has better stretching and elastic recovery properties, is warm, comfortable, dry, breathable, good in washability, pendulous, crease-resistant, environment-friendly and pollution-free, and is the ideal fabric for making high-grade casual clothes.