Multiferroic materials endowed with both dielectric and magnetic orders, are ideal candidates for a wide range of applications. In this work, we reported two phase transitions of MnI2 at 3.45 K and 4 K by systemically measuring the magnetic-field and temperature-dependent magnetization of the MnI2 thin flakes. Furthermore, we observed similar temperature and field-dependent behaviours for the magnetic susceptibility of MnI2 and electronic capacitance of the Ag/MnI2/Ag devices below 3.5 K. Considering the related theory work, we discussed the relationship between the antiferromagnetic and ferroelectric orders in MnI2. Our work reveals the in-plane magnetic and electric properties of MnI2 materials, which might be helpful for the further investigation and application of MnI2 multiferroics in the future.