The disclosure relates to a method for calculating surface electric field distribution of nanostructures. The method includes the following steps of: providing a nanostructure sample located on an insulated layer of a substrate; spraying first charged nanoparticles to the insulated surface; blowing vapor to the insulated surface and imaging the first charged nanoparticles via an optical microscope, recording the width w between the first charged nanoparticles and the nanostructure sample, and obtaining the voltage U of the nanostructure sample by an equation.