The invention discloses a micro electro mechanical system magnetic field sensor used for measuring the direction of a magnetic field. The micro electro mechanical system magnetic field sensor used for measuring the direction of the magnetic field comprises a substrate, a bottom electrode layer, a sacrificial layer, a metal layer and a silicon nitride layer which are sequentially overlaid from bottom to top, wherein the middle of the sacrificial layer and the middle of the metal layer are both hollow, a bent plate is arranged in the middle of the silicon nitride layer, a protruding plate extending outwards is arranged at one side of the bent plate, an anchor area is arranged on the top surface of the metal layer, the protruding plate is fixedly connected with the anchor area, the bent plate is located above the middle of the metal layer, a first capacitor, a second capacitor and a third capacitor are arranged on the bottom surface of the bent plate, a first capacitor lead, a second capacitor lead, a third capacitor lead and a metal wire which is distributed along the edges of the bent plate are distributed on the top surface of the bent plate, the two ends of the metal wire are respectively connected with a fourth bonding pad, the bottom electrode layer is connected with the metal layer, a fifth bonding pad is arranged above the edge portion of the silicon nitride layer, and the metal layer is connected with the fifth bonding pad. The micro electro mechanical system magnetic field sensor used for measuring the direction of the magnetic field is simple in structure and capable of measuring the direction and amplitude of the magnetic field.