This paper demonstrates a facile hydrothermal method using ethylenediamine (EDA) as a "shape modifier" for the controlled synthesis of rod bunch, decanedron, spindle, flakiness, and flowerlike NaCaSiO3OH microarchitectures. The set of experimental conditions is important to obtain adjustable shape and size of NaCaSiO3OH particles, as the change in either the amount of EDA/H2O or reaction time, or the amount of NaOH. Accordingly, the crystal growth mechanism during the synthesis process is proposed, and it is found that the EDA, acting as the chelating agent and shape modifier, plays a crucial role in fine-tuning the NaCaSiO3OH morphology. Morphology evolution process of flowerlike NaCaSiO3OH as a function of NaOH is also explained in detail. Eu3+/Tb3+ doped NaCaSiO3OH samples exhibit strong red and green emission under ultraviolet excitation, corresponding to the characteristic electronic transitions of Eu3+ and Tb3+. These results imply that the morphology-tunable NaCaSiO3OH:Eu3+/Tb3+ microarchitectures with tunable luminescence properties are expected to have promising applications for micro/nano optical functional devices.