Abstract: This invention relates to an illumination standard calculation method for a tunnel middle section based on safe visual recognition: (a) Setting the light environment of the tunnel middle section; (b) Placing a target object in the tunnel middle section; (c) Making a driver drive a motor vehicle at different speeds toward the target object, and measuring the visual recognition distances D required by the driver to visually discover the target object at different speeds; (d) Resetting the average brightness L of the tunnel middle section and repeating the steps (b) and (c) to obtain a plurality of different sets of visual recognition distances D and corresponding brightness values L; (e) Using the S model to fit the data of the plurality of sets of visual recognition distances D and brightness values L to obtain the formula of the relational model of D and L to be L=0.683/(5.