Ectoine,　so-called　tetrahydropyrimidine,　is　an　important　osmotic　adjustment　solute　and　widely　applied　in　cosmetics　and　protein　protectant.　Some　attempts　have　been　made　to　improve　the　ectoine　productivity.　However,　the　strains　with　both　high　ectoine　production　capacity　and　high　glucose　conversion　were　still　absent　so　far.　Aim　to　construct　a　strain　for　efficiently　producing　ectoine,　ectoine　synthetic　gene　cluster　ectABC　from　Pseudomonas　stutzeri　was　overexpressed　in　E.　coli　BL21　(DE3).　The　ection　production　was　improved　by　382　%　(ectoine　titer　increased　from　1.73　g/L　to　8.33　g/L)　after　the　rational　design　of　rate-limiting　enzyme　L-2,4-diaminobutyrate　transaminase　EctBps　(protein　engineering)　combined　with　the　metabolic　engineering　that　focused　on　the　enrichment　and　conversion　of　precursors.　The　final　strain　YW20　was　applied　to　overproduce　ectoine　in　fed-batch　fermentation　and　yield　68.9　g/L　of　ectoine　with　0.88　g/L/h　of　space-time　yield　and　the　highest　glucose　conversion　reported　[34　%　(g/g)].　From　the　fermentation　broth,　ectoine　was　purified　with　99.7　%　purity　and　79.8　%　yield.　This　study　successfully　provided　an　engineered　strain　as　well　as　an　efficient　method　for　the　industrial　biosynthesis　and　preparation　of　ectoine.