Abstract: Nano-hydrotalcite (Mg6Al2 (OH)16CO3·4H2O) was synthesized by mechanochemistry/crystallization method using brucite, Al(OH)3 and Na2CO3. The effects of dry milling time, milling speed and ball to powder mass ratio on crystal structure of hydrotalcite were studied, and the crystal structure and morphology were characterized by XRD and FE-SEM. Increasing dry milling time, milling speed and ball to powder mass ratio are all beneficial to the formation of nano-hydrotalcite. Well crystallized hydrotalcite, with regular hexagon shape and average particle size of 40 nm, can be successfully synthesized under 6 h of dry milling time, 2 h of wet milling time, 250 r/min of milling speed and a ball to powder mass ratio of 50:1. However, impurity phases will be found in the products if the experiment parameters kept increasing after the optimum ones.