A static magnetic field (SMF) assisted freezing system, which can generate a magnetic field with a strength of 0–180 Gs at the center of samples, was designed. The simulation and measurement methods determined that the extreme values of the internal magnetic induction intensity of the samples were less than 5% compared with that of the center. The deionized water and 0.9% of NaCl solution samples were subjected to a freezing experiment. The deionized water samples had maximum supercooling values at 20, 80, and 160 Gs; the degree of supercooling of the 0.9% NaCl solution increased with a magnetic field ranging from 0 to 100 Gs. The extent of supercooling tended to be stable within a range of 100–180 Gs. The SMFs could increase the nucleation time and decrease the phase transition time of the 0.9% NaCl solution. The extent of supercooling directly affected nucleation and phase transition time after analysis. Practical applications A magnetic field‐assisted refrigeration system is used as a new freezing technique for food cryopreservation. However, such system has drawn various conclusions from different laboratories. To explore the influence of magnetic fields on the freezing process, we design a SMF‐assisted freezing system, which can generate SMFs with a strength of approximately 0–180 Gs at the center of deionized water and 0.9% NaCl solution samples. This study use s a cooling method that is similar to the actual freezing process. This study demonstrates the positive effects of SMFs on the supercooling of liquids and provides a reference for further exploration.