Based　on　a　meso-mechanical　model　of　random　aggregate,　the　mesh　grid　was　partitioned　by　a　characteristic　unit　scale　of　the　material,　and　a　three-dimensional　meso-unit　equivalent　model　was　established　for　the　researches　on　the　damage　process　and　macro-mechanical　properties　of　heterogeneous　concrete.　The　nonlinear　finite　element　was　used　to　numerically　simulate　the　propagation　process　of　cracks　&　fracture　configuration　and　macro-mechanical　properties　in　wet-screened　concrete　specimen　under　uniaxial　tension　/compression　and　in　concrete　trisection　beams　under　bending　load.　The　simulation　results　were　compared　with　the　two-dimensional　results.　It　was　found　that:　1)　compared　with　the　plane　model,　a　3-D　model　could　simulate　the　damage　process　of　concrete　under　external　loads　more　realistic,　and　could　describe　the　macro-properties　of　heterogeneous　concrete　more　accurate,　and　the　computational　results　were　in　a　good　agreement　with　the　experimental　data;　2)　the　spatial　distribution　form　of　aggregate　had　a　great　influence　on　the　damage　process　and　damage　path,　but　little　impact　on　the　macro　elastic　modulus　and　strength　of　concrete;　3)　the　method　used　in　the　paper　had　high　efficiency,　compared　with　other　meso-mechanical　models,　such　as　a　random　aggregate　model.