Abstract: This paper studies the correlation between the growth in length and thickness of three puplar clones and the local climatic factor [combinations. Results of tests showed that the leading ecological factors giving rise to the variation of growth are ths annual average temperature, minimum temperature, accumulated temperature (≥10°C), cold index, annual precipitation and frost-free period. By means of successive regression, the optimum equations worked out for growth of the clones are as followes: 1nYH=4.122007-0.374162X1-0.120849x3+0.08949lX8 + 0.000963X9+0.007288X20 (Ry12m=0.93, F=13.57, I-69/55) 1nYH=1.564302-0.172733X3+0.013341Xe-0.021414X7+ 0.054196X8+0.00103X9+0.000748X10-0.004527X14 (Ry12,=0.95, F=10.19, I-72/58)On the basis of these results, the similarity levels between the six climatic factors at each of the forty-six experimental sites and those of the fixed sample site in Hanshou, Hunan were compared by the method of Fuzzy Mathematics. According to the value"S", the regions for the introduction of the southern type popular, can bs divided into four types: optimum area, favourable area, suitable area and unsuitable area as is described in the discourse.