N-butanol has been recognized as a promising alternative fuel in gasoline engines and has outstanding advantages over low-carbon alcohols in terms of energy density and miscibility. In this work, the comparative investigation on the spray behaviors of gasoline and n-butanol was carried out using a commercial gasoline direct injection (GDI) injector. The tests were carried out in a high-pressure constant volume vessel with the injection pressures from 6.0 to 15.0 MPa and ambient pressures from 0.1 to 0.5 MPa. High speed imaging and Phase Doppler Particle Analyzer (PDPA) techniques were used to examine the spray penetration and the droplet atomization process. The results showed that gasoline had a longer penetration length than that of n-butanol in most test conditions mainly due to the longer injection delay caused by the relatively small density and viscosity of gasoline. The relatively poor atomization quality of n-butanol (larger Sauter Mean Diameter) might further contribute for its larger droplet mean velocity than gasoline because less energy was consumed for atomization. Both increasing injection pressure and decreasing ambient pressure could enhance spray atomization and increase droplet mean velocity. However, once the injection pressure was beyond a certain value, its effect on droplet mean velocity was neglectible. The global velocity distribution presented an asymmetric feature with the spray axis in the far field possibly due to the jet-to-jet interaction.