The work aims to study the electroc-deposition, electrochemical behaviors and nucleation theory of nickel in eutectic solvent system. Cyclic voltammetry and chronoamperometry were used to study the electrochemical behaviors and nucleation theory of nickel deposition in Choline Chloride-Ethylene Glycol (ChCl-EG) eutectic solvent system. Scanning electron microscopy (SEM) was used to observe and analyze the micro-morphology of the nickel electrodeposited layer and EDS was adopted to analyze the elemental composition. The electrochemical window of ChCl-EG eutectic solvent was 2.63 V and the redox potential of nickel in ChCl-EG eutectic solvent system was respectively 0.79 V and -0.34 V. The cyclic voltammetry curves of different scanning velocities showed that when the scanning velocity was from 10 mV/s to 50 mV/s, Ep was independent of v and exhibited the characteristics of reversible reaction. When the scanning speed was increased from 50 mV/s to 90 mV/s, the trend of negative shift of Ep with the increase of scanning velocity v was observed and conformed to the characteristics of irreversible reaction. Nickel (Ⅱ) was a quasi-reversible reaction in ChCl-EG eutectic solvents. The chronoelectric curves were measured from -1.00 V to -1.08 V at "current hysteresis". Through the comparison of fitting chronoelectric curves and theoretical model, the electrocrystallization process of nickel (Ⅱ) in ChCl-EG system accorded with the Scharifker-Hill three-dimensional nucleation model by fitting the chronoelectric curve and comparing with the theoretical model. Nickel electrodeposit was distributed uniformly on copper substrate, and only nickel element was found in the coating. The electrodepositing process of nickel (II) in Choline Chloride-Ethylene Glycol (ChCl-EG) eutectic solvent system is quasi-reversible and the nucleation mechanism is the three dimensional transient nucleation. Through the Choline Chloride-Ethylene Glycol (ChCl-EG) eutectic solvent system, the nickel coating with high purity and uniform distribution can be obtained and the nickel coating has a particle size of 22.1 nm.