Currently, one of the main obstacle for CO₂ electrocatalytic reduction is the development of economical and efficient electrocatalysts. Among various electrocatalysts, Sn-based materials are especially appealing due to their low toxic and low cost for large scale use. However, the practical electrolysis of Sn-based electrocatalyst is severely hindered by its low energy efficiency and electrochemical stability. In this work, a coral-like Cu decorated Sn electrocatalyst is prepared by electrochemical reduction of Cu doped SnO₂ developed by a facile hydrothermal synthesis process. By introducing subsurface metastable oxide and incorporating Cu into Sn, the binding nature of electrocatalyst is effectively altered. Meanwhile, a well-designed coral-like matrix nanostructure contributes to an improved electrocatalytic activity and stability. With the protection of the matrix, the migration of atoms is constrained to a certain range, which resolves the sintering problem essentially. With ultra-small nanoparticles both spaced and connected by the matrix, facilitated electrolyte diffusion and unimpeded electron transfer are ensured at the same time. Therefore, the study of the coral-like Cu decorated Sn electrocatalyst may path a new way for the practical application in CO₂ electrochemical reduction.