Abstract: The technology of detecting weak magnetic field plays an indispensable role in lots of momentous areas，such as bio-medicine，resources exploration，military and aerospace engineering.It is the direction of the current magnetic measurement technology；to a great extent，it also represents the level of detecting magnetic field of a country.The major sensors of detecting weak magnetic field currently are Proton Magnetometer，Optical pumping，Atomic Magnetometer，Fluxgate，SQUID，Fiber-optic and Magneto resistance，which are used at home and abroad，and can be divided into scalar and vector type as the type of measuring magnetic field，according to analyzing their principle，property and state of technology and application，future research orientation and application foreground are all reviewed in this thesis，which will provide the reference for further theoretical research and engineering practice.