A porous tin particle and its preparation method are provided in the present invention. The method includes steps of: (a) performing a reductive (or reductive electrochemical) reaction on a tin particle which simultaneously reacts with lithium ions to form a tin-lithium (Sn—Li) alloy; and (b) performing an oxidative (or oxidative electrochemical) reaction on Sn—Li alloy to release the lithium ions therefrom, and the porous tin particle is formed. The porous tin particle could be further applied in manufacturing the electrochemical electrode for lithium-ion battery with longer cycle life and higher reversibility.