Objective:To investigate the incidence,etiology and diagnosis of acute kidney injury (AKI) in hospitalized patients. Methods:From October 2013 to September 2014,hospitalized patients meeting AKI (KDIGO,2012) definition and beyond 18 years old were screened for a cross-sectional study. The incidence,etiology,diagnosis and departments distributing of AKI patients were analyzed by SAS. Results:(1)The incidence of AKI was 1.6% (1401/87196),male to female ratio was 2.03:1,average age was 63.2±37.2,urban population accounted for 58.3%,the median length of stay was 18 (11,28) days,and median costs was 57.2(25.0-121.6) thousand Yuan. Patients whose renal function recovered completely or partially accounted for 66.5%,and 30 d mortality was 35.3% correspondingly. (2)AKI detection rate,timely diagnosis,delayed diagnosis,and missed diagnosis rate were 0.76%,44%,3.3% and 52.7%,respectively. Renal patients were characterized by highest AKI diagnosis rate (89.3%),while the surgical patients were at the lowest level with missed diagnosis rate of 75.1%. (3) The incidence of AKI varied by different departments:3.5% for nephrologie,1.3% for other internal,1.0% for surgery,and 18% for ICU. Nephrology,other internal,surgery and ICU accounted for 7.4%,37.1%,30.1% and 25.4% of the patients diagnosed with AKI,respectively. Cardiology,hematology,cardiothoracic surgery and ICU had a highrisk of AKI. (4) According to the etiology of AKI,prerenal,renal and post-renal accounted for 42.1%,52.2% and 5.7%,respectively. And prerenal was characterized with higher percentage of young patients with good original renal function; however,the missed diagnosis rate was as high as 85.7%. (5)AKI patients at stage 1,2 and 3 accounted for 38.0%,22.1% and 40.0%,respectively. As AKI stage upgraded,timely diagnosis rate was increased and missed diagnosis rate was decreased,however,it was accompanied by longer AKI stay,worse renal function recovery and higher 30 d mortality. Conclusion:AKI was generally characterized with common occurrence,low detection rate and high missed diagnosis rate. AKI criteria and recognition of high-risk factors needed to be spread among physicians in order to improve prognosis of AKI. Warning system for AKI should be established to improve early detection and diagnosis.