A thermal-moisture comfortable polyester FDY for summer use and a preparation method thereof are provided. The FDY is made of matting agents dispersed polyester via the steps of spinning melt metering, extruding via the compositional spinneret, cooling, oiling, drawing, heat setting and winding. The woven fabrics manufactured with the FDY possess a wicking height and an evaporation rate of larger than or equal to 135 mm and 0.22 g/h, respectively. The compositional spinneret is simultaneously provided with cruciform orifices and circular orifices, and the length ratio of cruciform orifice to circular orifice is equal to the product of their equivalent diameter ratio and a coefficient K, here equivalent diameter is the ratio of orifice cross-section area to its circumference and K ranges from 0.97 to 1.03, and the oiling involves the oiling agent containing 67.30-85.58 wt % of crown ether.