Abstract: Fitness is different from niche fitness, but they still have some comparability. Based on reviewing the both conceptions, the authors mend niche-fitness function by using the methods of niche center, niche breadth and environments variable, thus to analyze the relationship between them. The results show that, 1) the niche-fitness is relative to niche in a certain extent, and since niche-fitness is advanced to fitness, the physiology characteristics of plant seedlings could be used to construct niche-fitness as the index of fitness dynamic in the succession. 2) With the model built on the limitation factors of niche-fitness function, the limitation factors affecting the stages of species succession could be found out. The purpose of this work is to provide a new quantitative method to study the variation dynamic in the process of succession based on species' physiological characteristics.