L-threonine　transaldolase　(PsLTTA)　could　asymmetric　synthesize　β-hydroxy-α-amino　acids　(HAAs)　with　excellent　stereoselectivity,　while　the　poor　yield　limited　its　further　application.　Here　we　provided　a　combinatorial　strategy　to　improve　HAAs　production,　by　directed　evolution　of　PsLTTA　towards　enhanced　activity　and　introducing　an　acetaldehyde　elimination　system　to　avoid　acetaldehyde　over-accumulation.　A　novel　high　throughput　screening　(HTS)　method　for　evaluating　PsLTTA　activity　was　developed　and　applied　for　directed　evolution　of　PsLTTA.　Subsequently,　we　co-expressed　alcohol　dehydrogenase　and　formate　dehydrogenase　to　construct　an　acetaldehyde　elimination　system　to　remove　acetaldehyde　inhibition.　Moreover,　the　above　positive　strategies　were　integrated.　As　a　result,　the　(2S,3R)-p-methylsulfonyl　phenylserine　yield　reached　154.0　mM　and　with　94.6%　de　value,　the　highest　productivity　and　stereoselectivity　of　(2S,3R)-HAAs　reported　by　enzymatic　synthesis　so　far.　Taken　together,　our　studies　provided　an　efficient　and　green　route　for　chiral　synthesis　of　(2S,3R)-HAAs,　which　might　contribute　to　the　industrialization　production　of　these　useful　building　blocks.　©　2020　Elsevier　Ltd