We experimentally demonstrate a femtosecond mode-locked thulium-holmium(Tm-Ho)co-doped fiber laser incor-porating a saturable absorber(SA)based on a bulk-structured bismuth selenide(Bi2Se3)topological insulator(TI).The SA was prepared by depositing a mechanically exfoliated Bi2Se3 TI layer onto a side-polished optical fiber platform.Unlike high-quality nano-structured Bi2Se3 TI-based SA,bulk-structured Bi2Se3 with non-negligible oxidation was used as a sat-urable absorption material for this experimental demonstration due to its easy fabrication process.The saturation power and modulation depth of the prepared SA were measured to be～28.6 W and～13.4％,respectively.By incorporating the prepared SA into a Tm-Ho co-doped fiber ring cavity,stable soliton pulses with a temporal width of～853 fs could be generated at 1912.12 nm.The 3-dB bandwidth of the mode-locked pulse was measured to be～4.87 nm.This experimental demonstration reaffirms that Bi2Se3 is a superb base material for mid-infrared passive mode-locking even under oxidation.