The invention relates to a manufactured sand underwater dispersion resistant concrete, which comprises the following components in parts by weight: 100 parts of cement, 1-5 parts of underwater dispersion resistant additive, 2-20 parts of silica fume, 1-20 parts of coal ash, 1-10 parts of an enhancer, 140-200 parts of manufactured sand, 140-200 parts of macadam, and 30-50 parts of water. The preparation method comprises the following steps of firstly putting the manufactured sand, the macadam aggregate, the cement, the enhancer, the coal ash and the silica fume into an agitator, blending through dry mixing, then adding the underwater dispersion resistant additive to further blend through dry mixing, adding water into the material blended through dry mixing previously, stirring for 5-8 minutes, then preparing the manufactured sand underwater dispersion resistant concrete. The manufactured sand underwater dispersion resistant concrete has strong construction mobility, so that the problem of contradiction of mobility and dispersion resistance of the underwater dispersion resistant concrete is better solved, and therefore, the manufactured sand underwater dispersion resistant concrete not only has good dispersion resistance, but also has self-leveling and self-compaction construction mobility.