The invention relates to micro expansion concrete, which is mainly characterized in that the raw materials comprise the following ingredients in parts by mass: 265 to 270 parts of cement, 168 to 173 parts of water, 725 to 730 parts of sand, 1000 to 1010 parts of gravel, 75 to 85 parts of mineral powder, 75 to 80 parts of flyash, 10.00 to 10.50 parts of polycarboxylic acid water reducers and 36 to 38 parts of UEA-I type expanding agents. No structure crack is generated. The integral stability of the concrete structure is improved.