A control method for a binary SLA 3D printer comprising a binary light module and a galvanometric module, each light spot of the binary light module having only two levels, namely on and off, the binary light module being point light source and irradiating a light beam toward the galvanometric module, the control method resulting in a 3D printing method of a 3D object with more than two levels of applied light energy in each printing position of the 3D object, the method comprising following steps: a) retrieving a plurality of gray-scale slice images (802,822,842) corresponding to a 3D object, wherein a pixel value of each pixel of each of the gray-scale slice images (802,822,842) respectively represents a curing extent being expected of liquid modeling materials at a printing position corresponding to the pixel; b) mapping the pixel value of each pixel of each gray-scale image (802,822,842) from a pixel value full range to an accumulation value range for obtaining one of at least three accumulation values and making the accumulation value being obtained a printing parameter of each pixel, wherein the accumulation value range comprises the at least three accumulation values, the pixel value full range comprises all the pixel values of all the pixels of all the gray-scale images (802,822,842); c) selecting one of the gray-scale slice images (802,822,842) orderly; d) adjusting an accumulative lighting time of each of the printing positions in a modeling tank used to contain the liquid modeling materials of the binary SLA 3D printer by controlling the galvanometric module to change a plurality of angles of the plurality of prisms to make the light beam irradiate to the printing position corresponding to each pixel orderly according to the printing parameter of each pixel to control the binary light module to respectively irradiate each printing position in the modeling tank corresponding to each pixel based on a default curing power until the accumulative lighting time being consistent with the printing parameter of each pixel elapses for manufacturing one layer of physical slice model (320,322,340,342) according to the printing parameter of each pixel of the gray-scale slice image (802,822,842) being selected; and e) executing the steps c) to the step d) repeatedly until a physical 3D model corresponding to the 3D object is manufactured. a) retrieving a plurality of gray-scale slice images (802,822,842) corresponding to a 3D object, wherein a pixel value of each pixel of each of the gray-scale slice images (802,822,842) respectively represents a curing extent being expected of liquid modeling materials at a printing position corresponding to the pixel; b) mapping the pixel value of each pixel of each gray-scale image (802,822,842) from a pixel value full range to an accumulation value range for obtaining one of at least three accumulation values and making the accumulation value being obtained a printing parameter of each pixel, wherein the accumulation value range comprises the at least three accumulation values, the pixel value full range comprises all the pixel values of all the pixels of all the gray-scale images (802,822,842); c) selecting one of the gray-scale slice images (802,822,842) orderly; d) adjusting an accumulative lighting time of each of the printing positions in a modeling tank used to contain the liquid modeling materials of the binary SLA 3D printer by controlling the galvanometric module to change a plurality of angles of the plurality of prisms to make the light beam irradiate to the printing position corresponding to each pixel orderly according to the printing parameter of each pixel to control the binary light module to respectively irradiate each printing position in the modeling tank corresponding to each pixel based on a default curing power until the accumulative lighting time being consistent with the printing parameter of each pixel elapses for manufacturing one layer of physical slice model (320,322,340,342) according to the printing parameter of each pixel of the gray-scale slice image (802,822,842) being selected; and e) executing the steps c) to the step d) repeatedly until a physical 3D model corresponding to the 3D object is manufactured.