Well-dispersed MgAl 2 O 4 nanocrystalline was prepared by a convenient salt-assistant combustion process using low-toxic glycine as fuel, low-cost Mg(NO 3 ) 2 ·6H 2 O and Al(NO 3 ) 3 ·9H 2 O as raw materials. By changing the reaction condition such as glycine dosage, the amount of inert-salt, inert-salt types and calcinations temperature, the optimal conditions to synthesize MgAl 2 O 4 nanocrystalline were explored. The obtained results showed that parameters inert-salt and fuel dosage in the process have an important effect on the structure properties of samples. The obtained products were characterized by XRD and TEM. TEM images revealed that the products were composed of well-dispersed cube-like nanocrystals with the size of 60–80nm. The synthesis mechanism of MgAl 2 O 4 nanocrystals was discussed. The crystal growth dynamics of MgAl 2 O 4 nanocrystals was studied and the activation energy of MgAl 2 O 4 nanocrystals was 39.1kJ/mol.