The invention discloses a vision proportionality coefficient obtaining method based on machine vision, and the method comprises the following steps: (a), building a machine coordinate system (xj, yj) and a pixel coordinate system (xp, yp) based on machine vision recognition according to the movement directions of x-axis and y-axis, wherein the machine coordinate system (xj, yj) and the pixel coordinate system (xp, yp) are mapped to each other; (b), providing a Mark point in a camera view field, obtaining the initial pixel coordinates (xp1, yp1) of the Mark point and the machine coordinates (xj1, yj1) at this moment; (c), moving the Mark point to a second point in the view field, obtaining the pixel coordinates (xp2, yp2) of the second point and the machine coordinates (xj2, yj2), calculating and obtaining the rough vision proportionality coefficients: X'vs=(xj2-xj1) / (xp2-xp1), Y'vs=(yj2-yj1) / (yp2-yp1); (d), enabling the Mark point to be moved to a third point (xp3, yp3) in the camera view field according to the rough vision proportionality coefficients, obtaining the machine coordinates (xj3, yj3) of the third point, enabling the Mark point to be moved to a fourth point (xp4, yp4) and a fifth point (xp5, yp5) in the camera view field, obtaining the machine coordinates (xj4, yj4) and machine coordinates (xj5, yj5) at this moment, and calculating and obtaining the vision proportionality coefficients: Xvs=(xj5-xj4) / (xp5-xp4), Yvs=(yj4-yj3) / (yp4-yp3).