This study was designed to experimentally investigate the intensification effect of Al2O3/water nanofluid used as the spray fluid on the thermal performance of counterflow closed wet cooling towers (CWCTs). The mass fraction of nanoparticles was 0.1-1 wt % with nanoparticle dimensions of 10, 30, and 80 nm. Meanwhile, glycerin as stabilizer was used. After that the thermophysical properties of Al2O3 nanofluids were systematically measured. It was observed that the thermal conductivity, density, and viscosity of Al2O3 nanofluids increased with the increments of mass fraction. The results revealed that the maximum mass transfer coefficient was found to be 0.16 kg.m(-2) s(-1) for 0.5 wt % nanofluids and spray mass flow rate of 0.278 kg.s(-1). Moreover, the heat transfer capacity of the CWCT spraying 0.5 wt Al2O3 nanofluid could reach 1.22 times that of the water case, while the water consumption reduced about 15% under the same heat transfer capacity.