The invention relates to the technical field of in-situ characterization of mechanical properties and microstructure of materials and provides an in-situ micro mechanical test board. The test board comprises a motor execution mechanism, a spring auxiliary loading mechanism, a position sensing mechanism, a force sensing mechanism and a base, wherein the motor execution mechanism is fixed on the base, rotation output of a motor around the axial direction is converted into linear motion of the spring auxiliary loading mechanism through steering and transmission, the spring auxiliary loading mechanism applies a load to a sample, the position sensing mechanism detects the relative position variation, namely the sample deformation quantity, of the spring auxiliary loading mechanism in real time,and the force sensing mechanism detects a stress value borne by the sample in real time. The test board is advantaged in that a clamp supporting frame and a lead screw nut pair are elastically connected in the axial direction of a lead screw, on the basis, a load oscillator is additionally arranged, so fatigue performance testing of the sample and in-situ characterization of the microstructure morphology, chemical components, the crystal structure and the phase structure information of the material under the action of the fatigue load can be realized, the structure is reasonable and compact,and fine control under a force control mode is facilitated.