OBJECTIVE： To mine and evaluate the post-marketing safety alert signals of pegaspargase （PEG-ASP） and L-asparaginase （L-ASP），and compare the safety differences between them ，so as to provide reference for clinical safe and rational drug use. METHODS ： The adverse drug event （ADE） reports of PEG-ASP and L-ASP issued by FDA adverse event reporting system from Jan. 1st，2004-Jun. 30th，2020 were retrieved. BCPNN method was used to mine the safety signals of these two drugs under the condition that the lower limit of information component （IC－2SD）＞0 and the number of events ≥3. The medium and strong signals of two drugs with IC －2SD≥1.5 were evaluated and compared in 8 system organ class，such as gastrointestinal system ，hepatobiliary system ，blood and lymphatic system ，blood vessels and lymphatic vessels ， nervous system ，immune system ，metabolism and nutrition ，various examinations. IC value of specific ADE signal and its 95％ confidence interval were analyzed by time scanning spectrum. RESULTS & CONCLUSIONS ：The reports of PEG-ASP and L-ASP as suspected drugs were 2 324 and 3 824；67 and 68 medium and strong signals were included ，respectively. In gastrointestinal system，the common strong signal of PEG-ASP and L-ASP was necrotic pancreatitis. In hepatobiliary system ，both of them showed strong signal in venoocclusive liver disease ，and this ADE was not included in the drug instruction. In blood and lymphatic system ， common strong signals of the two drugs were febrile neutropenia ，coagulation disorder ，neutropenia and febrile bone marrow regeneration disorder ；in blood vessels and lymphatic vessels ，in addition to haemodynamic instability ，IC values of other signals of L-ASP were higher than those of PEG-ASP. In nervous system ，IC values of other signals of L-ASP were higher than those of PEG-ASP except for intracranial haemorrhage. In immune system ，anaphylactic reaction was a medium signal for L-ASP but was a strong signal for PEG-ASP. In metabolism and nutritional diseases ，except for tumor lysis syndrome ，IC values of other signals of L-ASP were higher than those of PEG-ASP. The results of time scanning spectrum showed that the signals of necrotic pancreatitis and coagulation disorder of PEG-ASP were stable ，while the signals of veno occlusive liver disease and hypersensitivity were unstable and needed to be observed ；above four signals of L-ASP were stable signals. When using PEG-ASP or L-ASP clinically ， close attention should be paid to the safety problems such as hypersensitivity ，coagulation disorder ，thrombosis，necrotic pancreatitis，venoocclusive liver disease and hypoproteinemia.