The present invention provides a method of eliminating optoelectronic cross coupling in scanning instrument. In cross light sensors, there is at least one light sensing set and the light sensing set includes one light sensing array and one adjacent light sensing array. The method of eliminating optoelectronic cross coupling includes obtaining the optoelectronic exposure amount obtained by the light sensing array, the optoelectronic exposure amount obtained by the adjacent light sensing array and migrated optoelectron amount in the scanning time t, substracting the migrated optoelectron amountfrom the optoelectronic exposure amount obtained by the light sensing array to obtain the corrected optoelectronic exposure amount of the light sensing array in the scanning time t as the correcting brightness value of the light sensing array in scanning pixels.