Paroxetine hydrochloride is an antidepressant and anxiolytic, a potent and highly selective 5-hydroxytryptamine reuptake inhibitor. 5-hydroxytryptamine is a neurotransmitter that is inextricably linked to our mood. Paroxetine hydrochloride can increase the concentration of 5-hydroxytryptamine in the salient interstitial space and enhance the function of 5-hydroxytryptamine in the central nervous system, thus playing an antidepressant and anxiolytic role, and in clinical practice this drug is mainly indicated for the treatment of depression and anxiety. It is important to note that the dosage must be determined by a specialist, and the main method of dosage is to gradually increase the dosage in the initial stage of use. If the patient needs to discontinue the drug, it must be in accordance with the doctor’s instructions to discontinue, this drug as other psychotropic drugs can not be suddenly stopped, if suddenly stopping the drug may occur more serious withdrawal reactions. In conclusion, paroxetine hydrochloride is an antidepressant and anti-anxiety drug, which acts on 5-hydroxytryptamine to exert antidepressant and anti-anxiety effects.