Ablation conditions play an important role in the femtosecond laser pulses induced nanostructures on ZnO. When 800 nm, 150 fs, 250 kHz femtosecond laser pulses were focused on the surface of ZnO in air, distilled water and ethanol, different nanostructures were produced. Experimental results show that femtosecond laser pulses induce nanowires with period of 180 nm in air, nanoballs constituted by ZnO nanowires are formed in distilled water, and obvious bifurcations are found in the nanostructures induced in ethanol. The results of Raman spectra indicate that the intensity of the fingerprint peak at 437 cm-1 declines after the irradiation, and the peak at 570 cm-1 is enhanced greatly. Surface nano-structuring evaluations and physical mechanisms under different conditions are analyzed in detail.