The research on the responses of tree growth to the hydrothermal factors in the marginal areas, such as the agro-pastoral ecotone, has played a vital role in revealing the ecological impacts of climate change. To probe into the influences of hydrothermal condition on the artificial coniferous forest growth, and the characteristic features of tree growth to its hydrothermal factors within different coniferous tree species, we chose the Saihanba Area, where the largest artificial coniferous forests in the Asian region were growing, as the sampling area. We sampled the tree ring data in high age-class artificial forests from two dominant afforestation species, the Larix principis-rupprechtii (larch) and the Pinus sylvestris var. mongolica (pine), and built up two standard tree-ring width chronologies for those two species based on lab analyses. Through examining the correlations between the chronologies of the two species and the local climatic factors including air temperature, surface temperature, precipitation, vapor pressure deficit, and so on, we have further revealed the similarities and differences of those two species in responding to the driving hydrothermal factors. The results are shown as follows. The growth of the larch was limited by the drought stress in June, July and September, and by the excessive rainfall in August, but promoted by the warm surface temperature and relatively more precipitation in winter. Similarly, the growth of the pine was confined by the drought stress resulted from the higher temperature in whole summer, as well as by the over-wet rainfall in August, but promoted apparently by the warm surface temperature in August, as well as by the relatively higher level in the lowest mean surface temperature in spring. The above results suggested that in Saihanba Area, the larch confronted more severe drought stress than that the pine did, but at the same time the larch underwent stronger stress in lower surface temperature than that pine did. Concerning the ever-increasing trend of temperature in the whole region in the coming future, we are inclined to predict that the Pinus sylvestris var. mongolica might be a better and more suitable tree species than that of Larix principis-rupprechtii for further afforestation and reforestation management in those large semi-arid regions such as Saihanba and the similar areas.