1. An image processing method of two-photon structured illumination point scanning microscopy, comprising the following steps: providing a laser light source, wherein the laser light source is focused onto a focal plane of a selected focal length, which is included in a detection target area of a sample-under-test, and the laser light source is a Near Infrared Pulsed Laser, meanwhile, the photon energy of the laser light source is half of the energy needed to let a molecule of the sample-under-test make a transition from ground state to a first excited state; performing scanning and recording, which is to use the laser light source, accompanied with an image recording system, to make a plurality of segmented scanning and image recording along two different directions respectively on the focal plane within the detection target area, so as to generate a plurality of structured illumination images of the detection target area; and performing image reconstruction, which is to perform reconstruction operation on the structured illumination images so as to generate microscopic image of the detection target area, including the sample-under-test; wherein the step of performing image reconstruction comprises the following sub-steps; performing image intensity adjustment, wherein intensities of the structured illumination images are adjusted to be consistent so as to generate a first image data; performing noise removal, wherein background noise of the image recording system is used as a base model for removing noise so as to remove the noise in the first image data and then to generate a second image data; performing data conversion, wherein the second image data is Fourier transformed to generate a third image data; performing a Multi-Phase Step Algorithm, wherein the third image data is processed with a linear simultaneous solution and phase estimation to generate a fourth image data; performing a shifted-weighting algorithm, wherein the fourth image data is calculated with an angular spectrum and filtered by at least one filter to filter out an optical transform function, wherein a shift in the fourth image data is modified to generate a fifth image data; performing Butterworth filtering treatment, wherein the fifth image data is passed through a Butterworth filter to generate a sixth image data; and performing an inverse Fourier transform on the sixth image data to obtain an image of the detection target area, including the sample-under-test.