Low-molecular-weight　organic　acids　(LMWOAs),　a　type　of　small　organic　molecules　with　one　or　more　carboxyl　groups　present　in　soil,　play　an　important　role　in　the　soil　ecosystem.　Greenhouse　soil　could　be　as　a　key　example　to　understand　LMWOA　distribution　and　its　ecological　effects　on　heavy　metals.　In　this　study,　54　soil　samples　and　24　vegetable　samples　were　collected　from　Wuqing,　Tianjin,　China,　to　investigate　the　distribution　of　LMWOAs　in　greenhouse　soil　and　its　effect　on　the　transfer　of　heavy　metals　from　soil　to　vegetables.　The　results　showed　that　the　mean　concentrations　of　lactic　acid,　acetic　acid,　formic　acid,　propionic　acid,　butyric　acid,　malic　acid,　and　oxalic　acid　detected　in　the　greenhouse　soil　were　5.00,　20.57,　0.62,　23.38,　0.64,　4.67,　and　29.03　mg/kg.　Except　for　formic　acid,　the　concentrations　of　LMWOAs　in　greenhouse　soils　were　higher　than　LMWOAs　in　field　soils.　The　content　of　oxalic　acid,　acetic　acid,　lactic　acid,　malic　acid,　propionic　acid,　and　butyric　acid　in　greenhouse　soils　is　2.3　times,　2.25　times,　1.82　times,　2.38　times,　1.38　times,　1.93　times　that　of　LMWOAs　in　field　soil.　LMWOAs　in　the　soils　had　obvious　surface　cohesion　characteristics.　The　correlation　between　LMWOAs　indicates　that　propionic　acid　has　the　same　origin　and/or　similar　variation　characteristics　as　malic　acid,　oxalic　acid,　acetic　acid,　butyric　acid,　and　lactic　acid.　Oxalic　acid,　formic　acid,　acetic　acid,　and　lactic　acid　have　a　significant　contribution　to　soil　acidification.　Accumulation　of　available　phosphorus　(AP)　and　available　potassium　(AK)　in　the　soils　may　result　in　increased　acetic　acid,　butyric　acid,　oxalic　acid,　and　lactic　acid.　The　above　results　indicate　that　LMTOA　has　different　effects　on　the　transfer　of　heavy　metals　from　soil　to　vegetable.　In　addition,　the　accumulation　of　LMWOAs　could　stimulate　the　transfer　of　Cd,　Zn,　and　Cu　from　soil　to　vegetable,　but　inhibit　the　absorption　of　Pb　by　vegetables.