The invention provides a preparation method of a durable hydrophobic fabric. The preparation method of the durable hydrophobic fabric comprises the steps of, firstly, preparing hydrophobic cross-linked polystyrene microspheres; secondly, performing surface modification on the prepared hydrophobic cross-linked polystyrene microspheres to form reaction-active -NCO functional groups on the surface of the hydrophobic cross-linked polystyrene microspheres; thirdly, grafting the modified hydrophobic cross-linked polystyrene microspheres onto the surface of a fabric to obtain the durable hydrophobic fabric. The prepared hydrophobic cross-linked polystyrene microspheres are stable in performance, simple in technical processes, low in raw material cost and easy to produce; by structuring a hydrophobic structure on the surface of the fabric through the surface-modified hydrophobic cross-linked polystyrene microspheres, significant hydrophobic effects can be achieved and maintained for a relatively long term; the processing temperature is mild and can effectively reduce influence on the original performance of the fabric; through a chemical bonding mode, the surface-modified hydrophobic cross-linked polystyrene microspheres are grafted to the surface of the fabric, so that the fabric can keep good hydrophobic effects after being washed for a number of times.