Abstract: Optical interferometry has played a crucial role in the development of physics and has been widely used in precision measurement and sensing techniques for various physical quantities. The development of quantum theory has brought about the first quantum revolution represented by semiconductor chips and lasers. The introduction of quantum concepts and technology in optical interferometry has once again revealed its merits and importance, becoming the foundation of the second quantum revolution represented by quantum information, quantum communication, and quantum sensing. This article first focuses on how quantum concepts have changed our view on optical interference since Einstein first introduced the photon picture of light more than 100 years ago. The intimate connection between multi-photon interference and quantum entanglement led to the development of quantum information. Further understanding of the effect of quantum noise in optical interferometry helps to develop quantum noise reduction technique for the enhancement of its precision. However, all these was based on the same hardware structure and measurement methods in optical interferometers since their invention about two hundred years ago. A recently implemented new type of quantum interferometer shows its advantages over traditional interferometers by changing the hardware and introducing quantum measurement techniques. It can break the coherence time limitation of traditional interferometers and promises applications in long baseline high-resolution astronomy and lidar technology.