The difference between depressive disorder and bad mood is mainly manifested in seven aspects: 1, the degree of low mood is lighter than that of depressive disorder, and it will not be accompanied by manic episodes or psychotic symptoms; 2, the course of bad mood is lengthy and usually lasts for more than two years, and even if it goes into remission, it often does not last for more than two months, whereas depressive disorder is mostly of self-limiting course and is prone to relapses; 3, the symptoms of bad mood have no circadian rhythm of changes; 4, the occurrence of poor state of mind is more closely related to psychosocial stress factors, and often there is a certain character basis, while depressive disorder can have psychosocial stress factors, but not necessarily, especially when relapse; 5, poor state of mind often take the initiative to seek treatment, while the willingness to seek treatment for depression disorder is generally; 6, poor state of mind of the interest in the decline, but not disappear, depressive disorder of the interest in the general decline, and even disappear; 7, the performance of depressive disorder is negative, the suicide rate is higher, while the bad state of mind even if there is a desire to die, but fear, worry.