The invention discloses a method and a related device for positioning a light-sensitive surface of an image sensor. The method comprises the following steps: selecting at least three preset detection points meeting preset geometric requirements in an environment of using integrating sphere-emitted light as a test light source, detecting light intensity values of the preset detection points, calculating a difference between the light intensity values of every two preset detection points, and judging whether each difference is in a preset range; when at least one difference is out of the preset range, adjusting a transverse shift and/or a longitudinal shift of the light-sensitive surface, re-measuring the light intensity values of the preset detection points, re-calculating the differences and judging until each calculated difference is within the preset range, determining that the light intensity values of all preset detection points are the same, and the center of the light-sensitive surface is aligned with that of an integrating sphere exit opening. The position adjustment process of the light-sensitive surface can be quantified and automated to improve the position adjustment accuracy of the light-sensitive surface, thereby ensuring that the center of the light-sensitive surface is accurately aligned with the center of the integrating sphere exit opening.