To improve 1,3-propanediol (1,3-PD) production and reduce byproduct concentration during the fermentation of Klebsiella pneumonia. Klebsiella. pneumonia 2-1 Delta ldhA, K. pneumonia 2-1 Delta aldH and K. pneumonia 2-1 Delta ldhA Delta aldH mutant strains were obtained through deletion of the ldhA gene encoding lactate dehydrogenase required for lactate synthesis and the aldH gene encoding acetaldehyde dehydrogenase involved in the synthesis of ethanol. After fed-batch fermentation, the production of 1,3-PD from glycerol was enhanced and the concentrations of byproducts were reduced compared with the original strain K. pneumonia 2-1. The maximum yields of 1,3-PD were 85.7, 82.5 and 87.5 g/l in the respective mutant strains. Deletion of either aldH or ldhA promoted 1,3-PD production in K. pneumonia.