In the past few decades, antibiotics have significantly improved patient health and enhanced the effectiveness of various treatments, including cancer therapy and organ transplants. However, the overuse of antibiotics has led to the emergence of drug-resistant bacteria, resulting in a decline in the effectiveness of antibiotics, creating an urgent need for alternative antibacterial agents. Antimicrobial peptides (AMPs) have emerged as a promising solution, with nearly 5000 natural AMPs identified from animals and plants. These peptides typically consist of 5–15 amino acids, exhibiting broad-spectrum antimicrobial activity and low toxicity, making them suitable candidates for therapeutic applications. This chapter primarily introduces the research and application progress of antimicrobial peptides from the aspects of their origin, classification and mechanism of action.