NOVELTY - A 1,3-propanediol is separated and extracted from fermenting solution by (A) removing bacterium to obtain fermenting solution, steaming to remove water and condensing; (B) adding glycerin to condensed fermenting solution, where adding amount of glycerin is 1-20 times of salt; (C) putting material of step (B) to rectifying tower 1, decompressing and rectifying; (D) taking material out of kettle top, putting into rectifying tower 2 to decompress and rectify; and (E) putting material of step (C) to distilling kettle 3 and distilling, recovering glycerin, cooling to obtain solid product.    USE - Method is used for separating and extracting 1,3-propanediol from fermenting solution (claimed).    ADVANTAGE - The method has purity of more than 99.5 wt.%, simple separating and purifying process, short flow, low cost, high purity and high yield.    DETAILED DESCRIPTION - 1,3-Propanediol is separated and extracted from fermenting solution by:    (A) removing bacterium to obtain clean fermenting solution, steaming to remove most of water and condensing to 1-10 times;    (B) adding glycerin to condensed fermenting solution, where adding amount of glycerin is 1-20 times of salt;    (C) putting material of step (B) to rectifying tower 1, decompressing and rectifying to steam 1,3-propanediol and byproduct 2,3-butanediol and remaining water from tower top and keeping glycerin and salt in the kettle at 1-20 KPa and reflux ratio of 0.2-5.0;    (D) taking material out of kettle top, putting into rectifying tower 2 to decompress and rectify at 1-70 KPa and reflux ratio of 2-40, discharging out of water, obtaining 2,3-butanediol product from side line, obtaining 1, 3-propanediol from kettle and refining to obtain 1,3-propanediol product meeting polytrimethylene terephthalate polymerizing requirement;    (E) putting material of step (C) to distilling kettle 3 to vacuum distill, recovering glycerin at 0.5-10 KPa and glycerin recovery rate of more than 95%, discharging residue out, cooling to obtain solid product and sending to burning furnace to burn.    The fermenting solution is obtained by using glycerin as the substrate.