The invention relates to a positioning construction device and method for audience seats in small theaters, auditoriums, conference centers and the like, and belongs to the field of engineering design. The present invention provides a light ray net spot positioning device and an axis positioning method thereof. The light ray net spot positioning device is installed on a marker post, and comprisesa center line positioning lamp, a light-transmitting grating plate and a light ray projection device. The center line positioning lamp is used for aligning with a central axis in a bounced audience seat field; the light-transmitting grating plate is arranged at the front end of the light ray projection device, and the radian of a mesh seam in the light-transmitting grating plate is matched with the radian of an audience seat to be set; and the light ray projection device projects longitudinal and transverse axes in the audience seat field onto the erected template through the mesh slits, and the template is matched with the audience seat field to be set. The light ray net spot positioning device and the axis positioning method thereof have the advantages that: 1, audience seats and corresponding axes are positioned more scientifically and quickly; 2, good operation can be achieved regardless of the oblique angle and the radian of the floor base plate, and the working efficiency is high; and 3, the debugging work is reduced, and the time and the labor force are saved.