The invention relates to hollow manganese dioxide nanoparticles and a preparation method thereof. The nanoparticles are prepared by taking PLGA nanoparticles (PLGA NPs) as a template, reducing potassium permanganate (KMnO4) by surface hydroxyl (-OH), growing a layer of manganese dioxide on the surface of the potassium permanganate, and then etching away PLGA by acetone. The prepared hollow manganese dioxide nanoparticles are controllable in particle size, adjustable in wall thickness, large in pore volume, simple in preparation method, low in raw material price and capable of serving as a carrier of a catalyst or an adsorbent, and conforms to the concept of green energy conservation; and as a drug nano-carrier, especially as a tumor microenvironment responsive drug nano-carrier, the hollowmanganese dioxide nanoparticles have the characteristics that drug is controlled to be released, a tumor treatment effect is improved, magnetic resonance imaging is achieved, and the practical valueis high.