The invention provides a method for increasing the concentration of 1, 3-propanediol in biological fermentation production, particularly relating to a method for adding an antibiotic, reducing transfer resistance when nutrition and metabolites enter or exit a cell, effectively promoting cell growth and increasing the concentration of the 1, 3-propanediol in the biological fermentation production. The technical process includes the steps that: a secondary seed culture solution is fed into a fermentation culture solution, meanwhile, the antibiotic which can improve cell permeability is added into the fermentation liquor, and the antibiotic is added to change the cell permeability so as to reduce the transfer resistance when the nutrition and the metabolites enter or exit the cell, thus improving the growth capability and the productivity of the thalli and increasing the concentration of the product, 1, 3-propanediol; furthermore, microbes are impelled to excrete the metabolites outside the cells, which decreases the accumulation of the metabolites in the cells, is favorable to eliminate the inhibition of products and by-products, especially reduces the inhibition of the 1, 3-propanediol to cell growth and cell catalytic activity, and at last, the concentration of the fermentation product, 1, 3-propanedio, is improved by 10 percent to 70 percent. The technical process is easy and simple, with low production cost.