Abstract: Under hydrothermal condition, γ-AlOOH nanowires with large aspect ratio can be synthesized successfully using mixed precipitant of NaOH solution and NH3·H2O solution. XRD and TEM were used to characterize the products. The results show that the γ-AlOOH nanostructure with different morphology can be synthesized by adjusting the ratio of NaOH and NH3·H2O. The lamellar γ-AlOOH with large size forming at the early stage of hydrothermal reaction developed into γ-AlOOH nanowires with large aspect ratio by rolling growth. The best γ-AlOOH nanowires with diameter of 10-30 nm, length of 1-2 μm, aspect ratio of 60-100 and apparent preferred orientation were obtained when the volume ratio of NaOH solution to NH3·H2O solution in the mixed precipitant was 1∶1, and holding time was 24 h.