In 2020, a total of 15 849 cases of medication error (ME) from 255 hospitals in 24 provincial administrative regions were collected in the National Monitoring Network for Clinical Safe Medication. The number of hospitals reporting ME increased by 8.97% compared with that in 2019 (234 hospitals), and the number of reported ME cases increased by 5.27% compared with that in 2018 (15 056 cases). In 15 849 cases of ME reports, 54 (0.34%) were classified as grade A, 12 297 (77.59%) as grade B, 3 010 (18.99%) as grade C, 358 (2.26%) as grade D, 72 (0.45%) as grade E, 52 (0.33%) as grade F, 0 as grade G, 5 (0.03%) as grade H, and 1 (0.01%) as grade I. Among the 15 795 patients with ME of grade B to I, 9 347 (59.18%) were male and 6 448 (40.82%) were female, aged from 1 day to 101 years; 1 714 (10.85%) were children (<18 years old), 8 355 (52.90%) were middle aged patients (≥18 to <60 years old), and 5 726 (36.25%) were elderly patients (≥60 years old). Among the 130 patients with serious ME (grade E-I) that caused injury, 77 (59.23%) were male and 53 (40.77%) were female, aged from 4 months and 14 days to 94 years; 16(12.31%) were children, 46(35.38%) were middle aged patients, 68(52.31%) were elderly patients. Among the 9 patients with serious ME caused by mistaken use of drugs, 7 were children, accounting for 43.75% (7/16) of all children with serious ME. The 54 grade A MEs did not involve person who triggered the MEs and place where MEs occurred. Among the 15 795 grade B-I MEs, 10 748 (68.05%) were triggered by physicians, 3 797 (24.04%) by pharmacists, 578 (3.66%) by nurses, 329 (2.08%) by patients and their family members, and 343 (2.17%) by other persons; the proportion of MEs triggered by patients and their family members increased year by year for 3 consecutive years (1.06% and 2.04% in 2018 and 2019, respectively), and 49.23% (64/130) of severe ME were triggered by patients and their family members; 6 830 (43.24%) occurred in clinics, 3 808 (24.11%) in hospital wards, 3 776 (23.91%) in pharmacies, 985 (6.24%) in pharmacy intravenous admixture services, 220 (1.39%) in the nurse stations, 161 (1.02%) in patients′ houses, 2 (0.01%) in the community health service stations, and 13 (0.08%) in other places; the proportion of MEs occurred in clinics and patients′ houses increased year by year for 3 consecutive years (37.32% and 0.41% in 2018, 37.74% and 0.89% in 2019, respectively). The top 3 contents of MEs were wrong drug class, wrong usage, and wrong quantity. The top 3 persons who discovered the MEs were pharmacists, physicians, and nurses. The top 3 factors causing MEs were lack of related pharmacologic knowledge, tiredness, and insufficient training of medical workers.