CdSe nanocrystals were prepared in a microreactor in which of reaction conditions can be precisely controled, and the controlability of particle size and photoluminescence properties, and the effect of reaction conditions on the properties of the product were examined. Particle size and photoluminescence properties were found to be highly reproducible, and the effect of the reaction conditions on particle growth and photoluminescence properties showed basically the same trend with that of a batch reactor, regardless of the shorter reaction time in the microreactor.