The invention relates to a nylon fiber with low surface frictional coefficient and improved hydrophobicity and a preparation method thereof. The preparation method comprises mixing modified nylon masterbatch and nylon chips in a mass ratio of (0.5-5):(95-99.5), and performing melt spinning to obtain the nylon fiber with low surface frictional coefficient, wherein the modified nylon masterbatch ismainly composed of, by weight, 37-88.8% of nylon, 10-60% of PDMS (polydimethylsiloxane) and 0.2-3% of POSS with amino side chains and is made by adding the materials proportionally into a mixer, mixing well, transferring to a twin-screw extruder and dicing. The prepared nylon fiber with low surface frictional coefficient and improved hydrophobicity has both dynamic frictional coefficient and stationary frictional coefficient of less than 0.3, has an angle of contact with water being greater than 71 DEG, has good durability, spinnability and good mechanical properties, and has a good application prospect.