Objective To prepare indocyanine green (ICG)-loaded platelet membrane biomimetic liposome (ICG-PLP) for tumor photothermal therapy, and to preliminarily evaluate its in vitro characteristics. Methods ICG-PLP was prepared by an ultrasound method, and its particle size and zeta potential were determined using a laser particle size analyzer. The encapsulation efficiency of ICG-PLP was detected by ultraviolet spectrophotometry. The photothermal properties of ICG-PLP were investigated under 808 nm near-infrared ray irradiation (2 W/cm²), and the retention of platelet membrane proteins was observed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The uptake of ICG-PLP by mouse macrophage RAW264.7, human non-small cell lung cancer cell A549, mouse melanoma cell B16-F10, and mouse breast cancer cell 4T1 was observed by a laser confocal microscope. Furthermore, the phototoxicity of ICG-PLP was detected by methyl thiazolyl tetrazolium assay, and the safety of ICG-PLP was preliminarily evaluated according to hemolysis rate and cytocompatibility. Besides, the in vivo retention time of ICG, ICG-loaded liposome and ICG-PLP in healthy SD rats was observed after tail vein injection. Results ICG-PLP was successfully prepared and its encapsulation efficiency, particle size, zeta potential, and the polydispersity index were (97.68±0.01)%, (109.77±0.76) nm, (－21.23±0.84) mV, and 0.22±0.01, respectively. ICG-PLP well retained the proteins on platelet membrane and showed good photothermal properties. Platelet membrane enhanced the uptake of biomimetic nanoparticles by tumor cells A549, B16-F10, and 4T1, and reduced the phagocytosis of biomimetic nanoparticles by macrophages. ICG-PLP exhibited a favorable photothermal therapy effect and could kill tumor cells. Additionally, ICG-PLP displayed a good safety. After intravenous administration, ICG-PLP prolonged the in vivo retention time of ICG in healthy SD rats. Conclusion ICG-PLP has been successfully constructed. It has a great potential in targeted drug delivery and tumor photothermal therapy.