The seed germination and plant growth of Sorghum sudanense Stapf, Amaranthus hypochondriacus L. and cowpea was performed investigate the biodegradability of PBS in soil extract liquid, discussed the effect of polymers, oligomers and monomers of PBS on germination and growth of plants. The results showed that Microorganisms in the soil extract liquid can degrade PBS and the pH of the degradation liquid does not change significantly; The degradation of polymer has little effect on plant growth; The degradation products of PBS inhibit the growth of some seedlings in initial stages, but have no effect in later stage; When the concentration of succinate is lower than 200mg·L−1, succinate has no effect upon plant seed germination and seedling growth, however, when it is higher than 500mg·L−1, seedling growth will be inhibited. When the 1, 4-butanediol concentration is less than 2000mg·L−1, it has no effect on seed germination and growth.