The invention provides a lung-targeting ceftiofur microsphere and a preparation method thereof, aiming at solving the problems that less medicine can reach the target part in the prior art, so that a great deal of medicine is wasted, the treatment effect is not remarkable, the toxic and side effect of the medicine is increased, and the probability of generating drug resistance is high. The technical scheme comprises: the microsphere takes ceftiofur as raw material and PLA as carrier material, and the weight ratio between the ceftiofur and the PLA is 1:0.5-10. The invention also provides the method for preparing the microsphere by emulsification. The microsphere prepared by the method has round appearance and shape, even grain fineness distribution, the average grain diameter of about 20mu m and higher medicine-loading rate. The microsphere can be used for treating lung infection of livestock and poultry with high effect, and leads the ceftiofur to be made into the lung-targeting microsphere so as to improve the concentration of the medicine at the lung tissues of animals and lead the medicine effect to be more remarkable, thus achieving the aims of slow release, long-term effect and target.