The role of cephalosporins is mainly antibacterial, there are four generations of cephalosporins, each generation has a different role in antibacterial. The first generation cephalosporins are mainly anti-Gram-positive bacteria, and the effect on Gram-negative bacteria is weaker, and the main side effect is more nephrotoxicity. The second generation cephalosporins have weaker antibacterial effect on Gram-positive bacteria than the first generation, and stronger antibacterial effect on Gram-negative bacteria than the first generation, with less nephrotoxicity than the first generation. The third generation cephalosporins are weaker against Gram-positive bacteria, but stronger against Gram-negative bacteria, more effective against Pseudomonas aeruginosa, and basically no nephrotoxicity. The fourth generation cephalosporins have stronger antibacterial effects on both Gram-positive and Gram-negative bacteria, and are not nephrotoxic.