Herein, three kinds of Li2CO3 and two kinds of MgCO3 center dot 3H(2)O crystals are easily synthesized in a homogeneousl ike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li2CO3 ranging from micro-flaky, flower to nanobranch, MgCO3 center dot 3H(2)O ranging from nanosphere to nanorod. Compared with coupled reaction and solvent extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small partides should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical industry Press Co., Ltd. All rights reserved.