Abstract: LiCoO₂ thin films with(003) orientation were deposited on stainless steel foil by magnetron sputtering. And the influence of power on the structure and electrochemical properties of LiCoO₂ thin films were investigated by XRD, SEM, Raman and electrochemical tests.Resultsindicate that in the range of 80~160 W, an appropriate increase of power is conducive to the bonding of Co and O atoms, which further improves the crystallinity of the films. When the power is 120 W, LiCoO₂ displays an excellent initial discharge specific capacity of 40.9 μAh cm^-2μm^-1 and with a capacity retention of 61.2% through 100 cycles. However, when the power is increased to 160 W,the lattice and crystallinity of LiCoO₂ will be compressed because the rapid deposition rate is difficult to match the diffusion rate of particles on the substrate surface. It blocks the diffusion of lithium ions inside LiCoO₂ , and the capacity reduces to 54.2% after 100 cycles.