The manifestations of severe mental disorders are as follows: 1. hallucinations in cognitive activities, such as hallucinations of hearing, smelling, seeing, touching, etc., delusions in thinking activities, such as feeling that others speak against him or harm him; 2. abnormal emotional activities, such as emotional indifference, lack of emotional communication with others, high or low emotions; 3. volitional behavior problems, such as strange, incomprehensible behavior, or even hostility, aggressive behavior, or lack of volitional activities, decrement, lack of active requirements, plans or intentions for work and life, etc.