The invention discloses a magnetic tunnel junction (MTJ) triaxial magnetic field sensor, which comprises an X-axis bridge magnetic field sensor with the X axis as the sensitive direction, a Y-axis bridge magnetic field sensor with the Y axis as the sensitive direction, a Z-axis bridge magnetic field sensor with the Z axis as the sensitive direction and an application specific integrated circuit (ASIC) chip connected and matched with the X-axis bridge magnetic field sensor, the Y-axis bridge magnetic field sensor and the Z-axis bridge magnetic field sensor. The Z-axis magnetic field sensor comprises a substrate and an MTJ element prepared on the substrate, the Z-axis magnetic field sensor clings to and covers the ASIC chip to form a clinging side, an included angle is formed between the clinging side and the lateral side adjacent to the clinging side on the Z-axis magnetic field sensor, the included angle is an acute angle or an obtuse angle, and the X axis, the Y axis and the Z axis are intersected with each other in orthogonality mode. By means of the structure, the MTJ triaxial magnetic field sensor is high in integrated degree, higher in sensitivity, low in power consumption, better in linearity, wide in dynamic range, better in temperature characteristics and strong in anti-jamming capability.