Magnetometry is an indispensable technology in human society. Magnetometers based on quantum sensing technologies have been developed in many quantum systems to realize high spatial resolution and sensitivity. Nitrogen?vacancy (NV) center in diamond is one of the quantum systems. This article provides an overview of the precision magnetic measurement technology based on the NV center system and its applications in various fields. Principles and advantages of using the NV center for magnetic field measurement are included in this paper. The research status of the magnetometry is also presented. Besides, practical applications of the magnetometry based on NV center in the field of materials imaging and life sciences are demonstrated. In the future, the magnetometry based on NV center will play an important role in the development of high sensirivity and spatial resolution vector magnetometer and facilitate more applications as geomagnetic mapping, nondestructive testing and others