Leveling agent, metal electroplating composition containing leveling agent, and preparation method and application of leveling agent

The invention discloses a leveling agent, a metal electroplating composition containing the leveling agent, and a preparation method and application of the leveling agent. The raw materials of the metal electroplating composition comprise a metal electroplating solution and the leveling agent, the metal electroplating solution comprises copper salt, acidic electrolyte, a halide ion source and water, and the leveling agent is a compound of formula I. The metal electroplating composition can be used in the process of printed circuit board electroplating and the copper interconnection electroplating process of integrated circuits, can realize the effects of no cavity and defect, low plating layer impurities, good homogeneity of plating, compact structure and small surface roughness, and has a good industrial application value.