Abstract: Nanomaterials of Manganese dioxide (MnO₂) has been widely researched as the supercapacitors. To improve its charge-discharge performance, the polythiophene/nano MnO₂ (PTh/MnO₂) composite was synthesized by the method of the in-situ chemical oxidation polymerization to modify the properties of MnO₂ in the present work. A series of PTh/MnO₂ composites were obtained by changing the component of polythiophene in the composites. Fourier transform infrared spectroscopy(FIIR), X-ray diffractometer(XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscopy(TEM) were used to characterize the chemical property, crystal structure, and surface morphology in detail. Afterward, the charge-discharge performances of the sealed button batteries were measured using CT001A battery test system, in which PTh/MnO₂ composite was used as the negative electrode. The results show that the morphologies of MnO₂ and polythiophene in the different PTh/MnO₂ composites are various. MnO₂ is uniformly distributed in PTh/MnO₂ composite when the component of polythiophene is 8 wt%~10 wt%. When the component of polythiophene is pretty high, however, the morphology of MnO₂ is affected substantially. Its original nanotubes almost disappear. The charge-discharge property of the buttery is also affected by the ratios of polythiophene in the PTh/MnO₂ composites. When the component of polythiophene is 20 wt% after 20 cycles, the capacity of the buttery is highest and reaches to 700 mAh/g. It is higher than that of the buttery in which nano MnO₂ was used as the negative electrode. It demonstrates that the presence of polythiophene in PTh/MnO₂ could enhance the charge-discharge property of MnO₂. The present work could supply the experimental base for the research on the applications of PTh/MnO₂ composite as the negative buttery.