To investigate the severity of stress, anxiety, depression and insomnia during the novel coronavirus disease (COVID-19) pandemic in adults outside Hubei Province, China. An online survey of psychological and sleep by using Questionnaire Star program from 5th to 19th February 2020 was conducted. The Impact of Event Scale-Revised was used to assess COVID-19 outbreak-related stress symptoms. Meanwhile, Questionnaires of Generalized Anxiety Disorder-7, Patient Health Questionnaire-9 and the Insomnia Severity Index were respectively used to assess the severity of anxiety, depression and insomnia symptoms prior to and during the COVID-19 pandemic. A total of 3 134 subjects were included. Among the included subjects, 15.5% (487), 24.9% (779), 28.7% (899) and 30.9% (968) of the subjects had COVID-19-related stress symptoms, anxiety, depression and insomnia after the COVID-19 outbreak, respectively. The severity levels of anxiety, depression and insomnia were significantly increased during the COVID-19 pandemic compared to prior to the outbreak (all <0.01). Furthermore, the subjects' stress response to the COVID-19 outbreak was an independent risk factor for increased anxiety, depression and insomnia after the outbreak. The COVID-19 outbreak resulted in related stress response and widespread increase in anxiety, depression, and insomnia outside Hubei Province, China in the general population. The aggravation of anxiety, depression and insomnia is associated with stress levels. Our data demonstrate that the widespread psychological and insomnia problems in the general population need to be addressed at the early phase of the pandemic.