Gram-positive bacilli specifically refer to a class of bacteria in the Gram-positive bacteria bacilli, common species include Bacillus anthracis, Bacillus diphtheriae, Bacillus tetani, etc. Clinically, except for some bacilli, most of the purulent cocci belong to Gram-positive bacteria. Bacilli and cocci differ in morphology and thus in nomenclature. Special clinical attention should be paid to the identification of Gram-positive and Gram-negative bacteria, which can affect the later therapeutic approach. Usually, Gram staining is used to identify Gram-positive bacteria, which retain the blue-purple color of the initial crystalline violet after staining, but Gram-negative bacteria are different and can be identified as such. Clinically, except for Mycobacterium tuberculosis, Gram-positive bacilli are more sensitive to penicillin. Therefore, penicillin is often used for treatment. Gram-negative bacilli are not sensitive to penicillin, so first identify the two before treatment can be carried out accordingly.