Narrow-distribution all-biological-base PBSA (biodegradable plastics) and preparation method thereof

The invention discloses a preparation method of a narrow-distribution all-biological-base PBSA (biodegradable plastics). The method includes the steps of 1), adding raw materials of biology-based succinic acid, biology-based adipic acid, biology-based butanediol and a compo-nd catalyst into a reaction container for nitrogen protection; 2), heating up a reaction system to DEG C in a temperature programming mode and pulping for 15-30 minutes; 3), heating up the reaction system to 180-240DEG C in the temperature programming mode and keeping the temperature for 1-4 hours; 4), after ending of an esterification phase, vacuumizing the system to 1000-10000Pa, and keeping the temperature at 180-240DEG C for 30-120 minutes; 5), between 180-240DEG C, vacuumizing the system to 80Pa below and continuing reaction for 60-300 minutes to obtain the product. By the arrangement, the PBSA prepared with the method has excellent use performance, problems about poor production stability and high cost in the prior art are effectivel