AIN with different morphologies, including thin film, nanowires, nanoneedles and nanochilies, depending on the controlled growth parameters, have been successfully synthesized by chemical vapor deposition technique. Field emission properties have been systematically studied. The experimental results show that all AIN nanostructures have good field emission properties. In comparison, AIN nano-chilies possess the best field emission properties with a low turn-on and threshold fields of 1.8 V/microm and 3.1 V/microm, respectively. The results suggest that the morphological modulation is an effective way to optimize field emission performance of nanostructures.