Quantum key distribution (QKD), based on quantum mechanical principles, provides a secure key agreement method for remote users and represents one of the most practical technologies in quantum information science. Integrated photonics offers an ideal technological platform for implementing QKD, demonstrating significant advantages in system scale, cost control, integration density, and scalability. This study focuses on integrated optical QKD, providing an overview of commonly used integrated optical material platforms and fundamental functional devices. Emphasizing practical system design and implementation, we summarize representative achievements in integrated QKD and analyze in-depth security issues of integrated QKD devices and systems. Additionally, we present perspectives on the development of quantum communication networks based on integrated devices.