The work aims to study anticorrosion properties of Ni-P-ZrO2 nanocomposite coatings in geothermal water. The Ni-P-ZrO2 nanocomposite coatings were prepared on stainless steel substrates by adding nano-ZrO2 particles into Ni-P electroless plating solution in the methods of ultrasonically dispersion and surfactants addition. Morphology and element composition of the nanocomposite coatings were analyzed with SEM and EDS. The anticorrosion properties of nanocomposite coatings were analyzed by adopting such electrochemical measurement technologies as Tafel and EIS in the simulated geothermal water at 50 ℃. The as-prepared Ni-P-ZrO2 nanocomposite coatings were dense and nonporous. Annual corrosion rate of the Ni-P-ZrO2 nanocomposite coatings in the simulated geothermal water was over 80% lower than that of the coatings on the stainless-steel substrate and over 20% lower than that of Ni-P coatings. Corrosion impedance, |Z|f=0.01 Hz, of the Ni-P-ZrO2 nanocomposite coatings declined sharply after 15 days of corrosion in the simulated geothermal water. Coating resistance, Rct, also decreased by nearly two orders of magnitude. The Ni-P-ZrO2 nanocomposite coatings have higher corrosion resistance compared with that of both Ni-P coating and stainless-steel substrate. Besides, the Ni-P-ZrO2 nanocomposite coatings containing the largest amount of ZrO2 nanoparticles have the best anticorrosion behavior. However, the corrosion resistance of Ni-P-ZrO2 nanocomposite coatings decreases markedly after a long period of corrosion.