Preparation process of cotton yarn

The invention relates to a preparation process of cotton yarn. The preparation process comprises the following steps: (1) manufacturing yarn units; (2) optimizing the yarn units, namely forming flat polyester filaments on the surfaces of the yarn units in a solution spinning manner to form wrapping layers, wherein the yarn units with the wrapping layers are basic yarn units; (3) cleaning the yarn units; (4) carrying out stain-resistant treatment; and (5) surface yarn forming treatment: treating the obtained multi-strand modified basic yarn unit by using compact spinning equipment according to a compact spinning process to obtain high-compactness cotton yarn, uniformly spraying the sizing agent onto the surface of the yarn unit through a sizing machine, and then drying and curing the yarn unit. The cotton yarn not only has better heat resistance, light resistance, high strength and good elasticity, but also has better wear resistance, wrinkle resistance, hygroscopicity, dyeing property and flexibility, and has