The dendrimers with four， eight and sixteen carboxylic methyl groups as outmost dendrons (denote as MCMD4、MCMD8 and MCMD16)were synthesized by divergent methodology using ethylenediamine and methyl acrylate as raw stuffs, and their terminal groups were turned into –COOK (denote as MCD4, MCD8 and MCD16) by basic hydrolysis. The results of scale inhibition experiment of the two hydrolysates which were used as scale inhibitors showed that MCD4, MCD8 and MCD16 has excellent scale inhibition on calcium carbonate, but the scale inhibition of MCD16 and MCD8 is much better then MCD4, the scale inhibitive rate of MCD4, MCD8 and MCD16 are 90%, 96% and 98% respectively. The structure of calcium carbonate scale inhibited by the scale inhibitor was investigated by FTIR and SEM, the scale inhibition mechanism of hyperbranched polymer with terminal carboxyl group was further explored.