Let D be a distributive lattice formed by subsets of a finite set E such that Ø,E∈D, with set union and intersection as the lattice operations. We define a simple split decompoisition of D intodistributive lattices Di⫅D(i=1,2) such that D is uniquely reconstructed from Di(i=1,2). Based on the combinatorial decomposition theory developed by Cunningham and Edmonds, we show that D can uniquely be decomposed (by repeated simple split decompositions) into a minimal collection of prime (indecomposable) distributive lattices and brittle distributive lattices, where each brittle distributive lattice corresponds to a poset represented by the Hasse diagram forming a star or a complete bipartite graph.