A superhydrophobic polypropylene (PP) coating on the surface of aluminum alloy coupons is unstable because of the existence of metastable state in curing process. Nano-titania particles were added into PP solution to form hierarchical micro- and nano-structures of PP coatings on the surface of aluminum alloy coupons. The morphology of the coatings was observed with Scanning Electron Microscopy (SEM), and the corresponding structure and components were investigated with Energy Dispersive Spectrometer (EDS) and X-ray diffractometer (XRD), respectively. The results indicated that nano-TiO2 particles are the main nucleation cores in the curing of the coatings; PP in solution is enclosed in these cores and crystallizes gradually. The coatings can preserve the stable micro- and nano-structure on six months due to the nucleation action of nano-TiO2 particles, and its durable water contact angle (WCA) is about 164 +/- 1.5 degrees.