Thick films are needed in micro-electro-mechanical systems (MEMS) as insulation, piezoelectric and ferroelectric materials. To form the thick film, powder jet deposition (PJD) method has been proposed. In the PJD process, microparticles are sprayed out from nozzle under the conditions of room temperature and atmospheric pressure, and make a film on the substrate. We have developed a new jet mechanism of double-nozzle type, and reported its results previously . In this study, we optimized the shape of the nozzle through investigating the influence of different dimensions and shape of the nozzle on the particles blasting velocity. As a result, it is found that nozzle diameter has a large affect on particles velocity.