The Mt. Helan is located in semi-arid area of North China. It is a typical region for dendrochronology study, to date, there are lots of climatic reconstructions for this region, but very few physiological response analysis though it is very important. In this paper, tree growth physiological responses to climatic factors are discussed by using the Vaganov-Shashkin model for the Mt. Helan region. The results could explain the relationship between tree-ring widths and climatic factors more reasonably. The materials used in the paper include meteorological data from three meteorological stations and one tree-ring width series.Considering the small difference of the elevation between AZQ meteorological station and tree ring site, the meteorological data are calibrated by a method described following: minus 0.9℃ from each datum of temperatures, and times 1.2 for each of precipitation data. In spite of that the parameters in Vaganov-Shashkin model have been fixed based on the research from the North America and Russia, they have been adjusted in terms of the factual situation of the research region. We therefore obtained two groups of parameters, which were applied in the V-S model separately, and the simulation results are quite similar. This indicates that the model is stable and has clearly physiological characteristics. There are certain correlations between tree-ring width series and climatic factors: positive with the precipitation from May to August; negative with the temperature from May to August, and positive with September to October. The simulation results indicate that the precipitation from the second ten days of May to August is insufficient to tree’s growth. With the decreasing of temperature in September and October, the main controlling factor turns from precipitation to temperature. We also, in this paper, found a strong relationship between ring widths and the ending of growing season, and weak correlation with the beginning of growing season.