Abstract: Objective To investigate incidence rate and risk factors of depression in patients with critical illness. Method 500 patients with critical illness in intensive care unit were investigated. All patients were classified as non-depression group and depression group by HAMD score. Related and depending risk factors were analyzed by statistic methods. Results Incidence rate of depression was 41.6%. The risk factors for depression including: single、disharmonious family relationship、uncare-for patients、low incoming、at one’s own expense、not permit visit、therapy by ventilator、hemodialysis、depression history、the time length of staying ICU、Ramsay and henry score. The sole risk factors were single、not permit visit、unsatisfactory state of clam and pain. Conclusion The incidence rate of depression for patients with critical illness in intensive care unit was very high, there were many important risk factors were related with depression, however the sole risk factors were single、not permit visit、Ramsay and henry score was lower than three.