Supersaturation is an important controlling factor for crystallization process and polymorphism. Droplet based microchannels and conventional crystallization were used to investigate polymorphs of L-gluatamic acid in this work. The results illustrate that it is easy to realize the accurate and rapid control of the crystallization temperature in the droplets, which is especially beneficial to heat and mass transfer during crystallization. It is also noted that higher degree of supersaturation favors the nucleation of a crystal form, while lower degree of supersaturation favors the nucleation of beta crystal form under droplet based microchannels for L-gluatamic acid. In addition, there is a different nucleation behavior to be found under droplet-based microchannels both for the beta form and alpha form of L-glutamic acid. This new finding can provide important insight into the development and design of investigation meanings for drug polymorph. (C) 2016 Published by Elsevier B.V.