The present disclosure discloses a micro-nuclear battery. The micro-nuclear battery comprises a base frame comprising a bottom, a top and a side wall; a cantilever structure having a free end hung in the air and a fixed end fixed to the side wall of the base frame and provided with a piezoelectric component thereon; and a radiation unit comprising an upper radioactive source and a lower radioactive source configured to emit electrons to the free end and respectively arranged at positions in inner surfaces on the top and the bottom of the base frame corresponding to the free end of the cantilever structure, wherein a width of the free end is greater than a width of the fixed end.