The invention discloses bare concrete. The bare concrete is characterized by being prepared from, by weight, 5-10 parts of surface modified nano-boron fiber, 5-10 parts of kaolin, 10-15 parts of illite powder, 20-30 parts of gravel, 5-10 parts of vermiculite sand, 20-30 parts of silver sand, 40-50 parts of Portland cement, 1-5 parts of a compound additive and 20-30 parts of water. The compound additive comprises, by weight, 20-25 parts of a phosphate borate copolymer, 2-5 parts of zinc citrate, 1-3 parts of pyrophyllite powder, 1-3 parts of wollastonite powder, 2-4 parts of porous magnesium silicate, 0.5-1 part of a defoaming agent, 0.8-1.5 parts of polyaminopropyl biguanide, 0.5-2 parts of hydroxypropyl cyclodextrin, 1-3 parts of an activator and 80-100 parts of water. The invention further discloses a preparation method of the bare concrete. The bare concrete is high in compressive strength, good in corrosion resistance, impermeability and crack resistance and excellent in comprehensive performance, and production and application are safe and environmentally friendly.