Spray pyrolysis (SP) is an attractive method for preparing uniform size and composition of particles because of its high production rate, continuous unit operation and simple apparatus. However, this method is limited for the production of submicron particles. It is difficult to produce nanosized of particles efficiently because the concept of the SP process deriving one particle from one droplet. The addition of salt-flux such as LiNO3 in the spray pyrolysis for producing smaller (nano) particles has been developed in our laboratory. In this study, LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. The utilization of LiNO3 salt on the preparation of ZnO by spray pyrolysis method is efficient to produce nanosized and enhance the crystallinity of the product. Regarding the influence of LiNO3, at the same processing condition, the mean particles size of LiNO3 assisted product is less than 1/9 times the mean particles size of conventional SP. Solid (dense), non-crinkle single crystalline ZnO particles having nanometer size were successfully obtained after washing the product. In addition, by using the same technique, the particle size can be controlled from 100-26 nm by operating temperature used and the residence time of the particles in the reactor.