In this paper, an electrochemical (EC) method to activate 316L stainless steel (denoted as 316L) surface for biomimetic calcium phosphate (Ca-P) coatings was reported. After EC treatment, a gel-like Ca-P film with a thickness of 150 nm was generated on the stainless steel surface after treatment, which was composed of amorphous phase of calcium phosphate with a large number of crystal nuclei of octacalcium phosphate (OCP) inside. This Ca-P thin film is the main factor that causes Ca-P formation under biomimetic condition. The effectiveness of EC treatment was also compared with alkali heat (AH) pretreatment in producing biomimetic coating on 316L. A uniform Ca-P coating formed on EC treated samples after samples were immersed in saturated calcium solution (SCS) for several hours, while only some island-like deposits were found on the sample surface with AH treatment followed by immersion in SCS for several days. This work has explored a novel and effective pretreatment method to activate 316L implant surface, which can be expected to be applied to activate other metal implants.