Abstract: In order to investigate the formation process of freshwater cultured pearls, the surface microtopography characteristics of abnormal-shape freshwater cultured pearls by inserting technology are observed by using the environmental scanning electron microscope(ESEM).The results show that the shapes of aragonite templates with layer arrangement in the nacreous layer of abnormal-shape freshwater cultured pearl samples are various, multilayered and orderly.At the initial stage of the nacreous layer growth, the mantle cells of Hyriopsis cumingii secrete the protein on surface of the nucleation pieces, which provides the matrix and limited space for the minerals in advanced stage, and plays a vital role in mineral nucleation, space arrangement and crystallization orientation.The protein also functions as determining whether there would be homogenous mineral in ion accumulation.A spiral structure, similar to that of seawater pearls or Hyriopsis schlegeli cultured pearls, appears on the surface of the freshwater cultured pearl samples, which might be affected by the regulatory functions of the protein in the growth process.As a result, the aragonite accumulation in different locations is variable, the aragonite crystals grow in the specific lattice direction, and their crystallization orientation and nucleation pattern are controlled, leading to their spiral accumulation and spiral appearance.