The invention provides composite fiber containing a thermoplastic polymer composition and a production method thereof. The composite fiber comprises 15-85 wt% of a soluble thermoplastic polymer and 85-15 wt% of a difficultly-soluble thermoplastic polymer. In the fiber fracture section, the two compositions shows multi-segmentation arrangement, all segmentation parts of the soluble thermoplastic polymer are mutually independent, and the segmentation parts of the difficultly-soluble thermoplastic polymer are in mutual connection. After the fiber is used to prepare fabric, dissolve-out polymers in the fiber is removed through dissolve-out processing under proper alkali dissolution conditions, and a tiny groove structure is formed along the axial direction of the difficultly-soluble thermoplastic polymer in the fabric, so that the fabric has good water-adsorption rapid-drying performance.