There are strict requirements for the deformation of glass plate in the vertical direction in the process of on-line detection of LCD glass substrate. In order to determine the nozzle requirements in index spacing, the theoretical analysis of the LCD glass plate supported by gas suspension was carried out based on the small deflection bending theory of elastic sheet, and the LCD glass sheet maximum deflection formula under the action of the blowing and suction nozzles was derived. The analysis shows that the maximum deflection is proportional to the square of through-hole spacing and degree of load; The load distribution and the maximum displacement of the glass substrate under different nozzle through-hole spacings were obtained by the Fluent simulation on the LCD glass substrate gas suspension system. The maximum displacement of the glass plate, pressure distribution of the gas film surface and economic aspects were considered to obtain the range of the through-hole lateral spacing of the gas film unit. A type of nozzle layout parameter of the optical detection apparatus for the LCD glass substrate using gas suspension transmission was presented; the reasonable nozzle spacing should be between 20 mm and 25 mm.