The invention relates to N-heterocyclic substituent-containing antibiotics, their preparation, and their use. Disclosed are sodium and potassium salts of 7-(α-((N,N′-diisopropylamidino)thio)acetylamino)-3-(((1,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triazin-3-yl)thio)methyl) cephalosporanic acid as presented by the general structure (I), their preparation, and their use. The antibiotics of the invention can be used to treat diseases caused by Gram-positive or Gram-negative bacteria such as septicaemia, gastrointestinal tract infection, and urinary tract infection. They have increased half-life in blood and lowered toxicity. They can reduce the frequency of drug use and lower medical treatment costs. They have improved stability and can be stored at ambient temperatures. The method of the invention is simple, and it produces high purity products which can meet the requirements of clinical use.