Compartmentalization of the subcellular space increases the efficiency of many biological processes by concentrating and delivering the required components to a confined space within the cell, and phase separation plays a key role in the membrane-less compartmentalization and serves as a linker for this disorder to order transition. Influence of magnetic field on the liquid-liquid phase separation behavior has been reported in different systems, whereas the mechanism is still under debate. From a phenomenological viewpoint, crystallization is phase separation in a thermodynamically metastable supersaturated system. Glucose, calcium and sodium are essential to various physiological processes, such as regulating the electrical potential of cells and maintaining the cellular homeostasis and function. Investigation of the magnetic field effects on crystallization of these substances may provide insights on how magnetic field facilitate disorder to order transition, and therefore affect phase separation in biological systems. In this study, the processes of cooling crystallization of glucose and calcium gluconate and evaporative crystallization of sodium chloride with or without magnetic field being applied were recorded and compared. Our data suggested that magnetic field increased the weight of precipitated crystals of all three substances, but effects of different magnetic fields differed in degree. The number of precipitated crystals of glucose and calcium gluconate, but not sodium chloride, was affected by magnetic field as well. The evaporation rate was also affected differently by magnetic fields in a concentration dependent manner. This study not only provided a theoretical basis for the further study of the biological effects and mechanism of magnetic field, but also provided a new idea for improving the crystallization efficiency in industrial production.