In order to improve the injection efficiency of liquid micro injection and the injection directivity of powder micro injection, a borosilicate capillary and a quartz glass tube are chosen as raw materials to design and manufacture the in-line combined micro nozzle and the coaxial combined micro nozzle based on stable drawing and forging process. Using these tow combined micro nozzles, liquid and powder micro injection experiments are performed on a micro injection experiment system based on the digitalization of microfluidic technology. In liquid micro injection experiment, the regular and uniform droplet array with a average diameter of 180 μm and no satellite droplets is prepared with one injection in a 4×2 in-line combined micro nozzle, by which the efficiency of micro injection under in-line combined micro nozzle is improved as compared with that of single micro nozzle. In powder micro injection experiment, the injection angle is reduced from 33° to 10° and the width of formed powder line is decreased from 450 μm to 300 μm as compared with that of single micro nozzle. The results indicate that the powder flow of the major micro nozzle in coaxial combined micro nozzle is constrained with the assisted micro nozzle and the injection directivity is improved greatly.