A novel biodegradable sodium poly(aspartic acid) (PASP) hydrogel with microporous structure was manufactured using electrospun polysuccinimide (PSI) nanofibers. PSI is the intermediate of sodium PASP and could be electospun into nanofibers easily. Firstly, PSI nanofibers were prepared from PSI/N, N-dimethylformamide solution. Then the PSI nanofibrous mats were crosslinked and hydrolyzed to obtain biodegradable microporous sodium PASP nanofibrous hydrogels. The chemical structures, morphologies and pore sizes of PSI nanofibrous mats and microporous sodium PASP nanofibrous hydrogels were investigated. Moreover, the properties of PSI electrospinning solutions, and the swelling ratio and biodegradability of sodium PASP hydrogels were also examined. The results showed that the swelling ratio of microporous sodium PASP nanofibrous hydrogels achieved to 21.0-24.3 g/g and were obviously higher than that of the sodium PASP casting film, reporting a swelling ratio of only 4.6 g/g. When the microporous sodium PASP nanofibrous hydrogel was immersed in water, it exhibited quick absorption and morphological robustness. The microporous sodium PASP nanofibrous hydrogel showed 83 wt% weight loss after 7 days of trypsin catalyzed biodegradation, and the SEM analysis demonstrated the significant morphology change of the microporous sodium PASP nanofibrous hydrogel during the biodegradation.