The invention discloses the components and preparation method of beta-lactam injection. The beta-lactam injection comprises 5 to 20 percent of beta-lactam antibiotics, 0.05 to 5 percent of suspending agent, 0.005 to 0.3 percent of antioxygen, 0.1 to 0.2 percent of nonionic surfactant and the balance of vegetable oil or grease for injection. The injection can be used for preventing and curing animal bacterial infectious diseases and can be injected hypodermically or in muscle and be applied through breast for a few times. The preparation method provided by the invention comprises: firstly, making the antibiotics and the antioxygen into micro powder and making the suspending agent into fine powder; secondly, adding the vegetable oil or grease for injection, which is sterilized at high temperature, into the fine powder of the suspending agent, heating the mixture, uniformly mixing the mixture and keeping the mixture in a sterile environment to cool the mixture to room temperature for later use; and finally, transferring the prepared oil or grease added with the suspending agent to a colloid mill, adding medicament micro powder, the antioxygen and the non-ionic surfactant with stirring, and performing uniform mixing and sterilization to obtain the beta-lactam injection.