A series of peptide and Schiff bases (PSB) were synthesized by reacting salicylic acid, primary diamines with salicylaldehyde or its derivatives, and 40 of which were newly reported. The inhibitory activities against Escherichia coli beta-ketoacyl-acyl carrier protein synthase III (ecKAS III) were investigated in vitro and molecular docking simulation also surveyed. Top 10 PSB compounds which possess both good inhibitory activity and well binding affinities were picked out, and their antibacterial activities against Gram-negative and Gram-positive bacterial strains were tested, expecting to exploit potent antibacterial agent with broad-spectrum antibiotics activity. The results demonstrate compound N-(3-(5-bromo-2-hydroxybenzylideneamino)propyl)-2-hydroxybenzamide (2d) can be as a potential antibiotics agent, displaying minimal inhibitory concentration values in the range of 0.39-3.13 microg/mL against various bacteria.