The effects of macronutrients (NO3 −, NH4 + and PO4 3−) on cell growth and triterpenoids production inCentella asiatica cell suspension cultures were analyzed using the Box-Behnken response surface model experimental design. In screening and optimization experiments, PO4 3− as a single factor significantly influenced cell growth where increasing the phosphate level from 0.1 to 2.4 or 2.6 mM, elevated cell growth from 3.9 to 14–16 g/L. The optimum values predicted from the response surface model are 5.05 mM NH4 +, 15.0 mM NO3 − and 2.6 mM PO4 3−, yielding 16.0 g/L cell dry weight with 99% fitness to the experimental data. While the NH4 +-NO3 − interaction influenced cell growth positively in the optimization experiment, NH4 + and NO3 − as single factors; and interactions of NO3 −-PO4 3−, NH4 +-PO4 3− and NH4 +-NO3 − were all negative in the screening experiment. Cell growth and the final pH level were positively affected by PO4 3−, but negatively affected by NH4 + and NH4 +-PO4 3− interactions. The different effects of factors and their interactions on cell growth and final pH are influenced by a broad or narrow range of macronutrient concentrations. The productions of triterpenoids however were lower than 4 mg/g cell dry weight.