In order to maintain the stability and persistence of clonal population, clonal plant can make good use of favourable patches or avoid adverse patches by clonal plasticity regulation if the environment conditions are changed. Meanwhile the fitness of population is improved. The adjusting mechanism of clonal plasticity includes external mechanism and internal mechanism. However, researches about clonal plants growth regulation mainly focus on the external mechanism.In order to understand the intrinsic mechanism of clonal growth regulation of Hippophae rhamnoides L.ssp.sinensis, growth and biomass increment in response to Exogenous Phytohormone, IAA in combination with CTK, was studied by 3×3 regression design. The results showed that, (1) the regularity of growth traits in response to the amount of Phytohormone showed the convex surface models. Each growth index has a maximum value. The growth was improved as the increasing of amount of IAA and CTK in front of maximum value, and the growth was decreased as the increasing of amount of IAA and CTK in back of maximum value. (2) The regularities of different growth indexes in response to the amount and ratio of Phytohormone had some differences——the higher amount of IAA was advantage to the height growth of stem, the higher amount of CTK was advantage to the diameter growth and crown width growth, the nearly amount of IAA and CTK beneficial to the accumulation of population biomass. (3) The growth potential of Hippophae rhamnoides L.ssp.sinensis was plenty developed when the amount of Exogenous Phytohormone was feasible. The individuals were tall and the amount of daughter ramet was increased. It was beneficial to not only population improve the lock-in and occupation and utilization to environment resource but also advance the ability of exclude other plants invading. When the amount of Exogenous Phytohormone was too high or too low, the individuals were short and the amount of daughter ramet was reduced to be beneficial to weaken the competition among individuals. This result provided clue to the internal adjusting mechanism of clonal growth. (4)The best amounts and rations of IAA and CTK, reasonable Phytohormones ranges and op-curve lines were gained based on Phytohormone effect equations of different growth index. (5)The increment of daughter ramet was not only significantly related to diameter increment and crown width increment but also highly related to population biomass. It showed the individual growth and daughter ramet generation were accelerated by the feasible amount of IAA and CTK.