With the vigorous development of 5G, artificial intelligence (AI), the internet of things (IoT), and the shrinking size of semiconductor processes, the data processing capacity and other performance of the terminal and servers processors have increased rapidly, which puts forward new requirements for power management chips. Multi-phase parallel converter has great advantages in low-voltage and high-current working condition, fast transient response, etc., and is considered one of the best solutions to the power management challenge of the processors. Starting from the principle and advantages of multi-phase buck converters, the development and latest research progress of key technologies, such as multi-phase current balancing methods, control modes and efficiency improvement, were studied. Finally, the key development trends and challenges of multi-phase buck converters were showed.