A reversible bending phenomenon of Si3N4 nanowires on the conductive carbon–formalin microgrid under an illumination of electron beam was observed using a transmission electron microscope. The nanowires exhibit high flexibility. The bending deflection is approximately proportional to the square of the current density (J) of the electron beam. The bending strength of Si3N4 nanowire is much higher than that of bulk Si3N4 materials. The force that bent the nanowires may be an electrostatic force.