In order to establish the relationship between subjective sense and physical measurement in lighting engineering, the qualitative and quantitative analyses are connected through generalized Weber - Fechner Law. For practical application problems of lighting engineering, a proximate function of subjective sense deduced from physical measurement is brought forward. The experiment in advertising lighting shows that the result of this function is more exact and more closely to the practice than others. Using this proximate function, the illumination level, corresponding to given satisfaction level, can be found. In other words, the physical measurement corresponding to given subjective sense can be evaluated by using this proximate function, accordingly the design of lighting project can be directed reasonably.