With the improvement of people's living standard and the integration of sports and health philosophy in daily life, people have higher and higher requirements on the comfort and function of textiles. In summer, people are willing to wear and contact items with low temperature. Cool fabrics can make the skin surface that touches the fabric feel the temperature difference at the moment of touch, resulting in a cool feeling of contact. What's more, the global greenhouse effect is increasing year by year. In order to actively cope with climate change and reduce the use of refrigeration equipment, cool fabric has also become a hot spot in the development of energy-saving clothing. In addition to the need for cool feeling, people are more prone to sweat when doing sports in summer. The traditional high moisture-absorption fabric can absorb but cannot discharge sweat. As a result, the unidirectional water-transfer technology which can improve the thermal and wet comfort of clothing comes into being. This technology can transfer the sweat from the inside of the fabric to the outermost layer through the matching of hydrophilic yarns and hydrophobic yarns and the fabric structure design, so that it is not easy to penetrate along the original path. In this way, the the skin surface can maintain dry. This can improve the air permeability and water permeability of fabrics worn in summer, and help the human body dissipate heat quickly. The purpose of this paper is to develop a series of lightweight and cool fabrics with unidirectional water-transfer function. In order to overcome the discomfort of skin adhesion caused by poor water absorption of conventional cool fibers and the inability to effectively absorb and expel sweat, we selected the cool polyethylene (PE) and its composite fiber with skin-core structure (PE/PP) and modified polyester (including low-temperature cationic polyester and microfiber polyester) according to the principle of unidirectional water-transfer technology. The fabric can achieve the effect of unidirectional water-transfer performance by combining with the weft-knitted double-sided structure that can form a unilateral mesh through the wetting gradient formed by the inner and outer layers of the fabric, so that the skin surface stays dry and improves its cool touch. In this paper, five kinds of tissue structures were designed, and the fabric structure was simulated by combining the Internet knitting CAD system IKDS. By adjusting the fiber raw materials and yarn configuration, a series of weft-knitted lightweight fabrics with single cooling sensation and double-sided and multi-needle passage were developed. Finally, the contact cooling sensation, the performance of unidirectional water-transfer, moisture permeability and air permeability were tested, and the fabric performance was comprehensively evaluated by the objective weight method. The results show that the skin-friendly surface of PE/PP skin-core structure composite fiber knitting has excellent contact coolness, and when the skin-friendly side forms unilateral mesh with concave and convex shape, it can effectively reduce the adhesion area between the fabric and the skin, significantly improve the unidirectional water-transfer performance and contact with cool feeling, and meet the needs of the fabric's thinness, which provides a new idea for the development of summer sports fabrics. At present, the unidirectional water-transfer performance and contact cool function of most clothing on the market is realized by adding high dose chemical additives in the finishing, which not only limits the number of washing, but also has potential dangers for human safety. However, the selection of cool fiber and the combination of unidirectional water-transfer structure is more stable, safe and healthy. This kind of fabric is not only effective in the field of clothing, but also will develop to multi-functional and intelligent in the future to meet the needs of consumers in many fields. [ABSTRACT FROM AUTHOR]