Abstract: This paper studied the influence of porous nickel cathode microstructure and wettability on the characteristics of electrolytic hydrogen bubbles in the electroflotation. The porous nickel electrode was treated by acid etching and surface modification of fluorosilane. The influence of the microstructure and wettability of the treated porous nickel cathode on the size, concentration and rising speed of hydrogen bubble was investigated. The results show that acid etching can improve the surface roughness of porous nickel cathode materials and increase the cracks and pores produced by etching Ni particles. The hydrophilicity of the porous nickel cathode has been increased significantly after acid etching, and the surface hydrophilicity also has been increased with the continuation etching. The fluorosilane modification can increase the hydrophobicity of the electrode surface, and the fluorosilane modification become more significant after the etching pretreatment of the electrode. the more hydrophilic the electrode surface, the smaller in size, the higher in concentration and accumulation the produced hydrogen bubble, and vice versa. In the scale range of the hydrogen bubble produced on the porous nickel cathode, the rising speed of bubble is linearly related to the size. The larger the bubble size becomes, the quicker the rising speed increases.