Abstract: Quantum sensing is one of the chief areas of current quantum technology, and has the longest history, the highest maturity, and the widest applications. This paper is the second part of “Quantum Sensing” review, and mainly focuses on the key technologies and typical examples of quantum sensors. The preparation, control and detection of quantum states, together with the core principles and technical basis of quantum sensing are summarized. Typical quantum sensor technologies such as those involving frequency standards, electric and magnetic field sensors, gravity and inertia sensors are introduced in detail, as well as the basic principles, development platforms, and current state-of-the-art.