Objective:To investigate the Knowledge-Attitude-Behavior (KAP)status and the influencing factors of protective behavior on COVID-19 among mobile phone users in Hainan province. Methods:From January 31 to February 8, 2020, questionnaires using the online questionnaire star platform were distributed to 901 mobile phone users in Hainan Province via WeChat, QQ and other social software channels, and 804 valid responses were collected. Results:The average score of knowledge was (61.22 ± 22.453),and 71.5％ of participants with good awareness of COVID-19; the average score of COVID-19 related attitude was (10.69±2.26), and 72.6％ of participants with supportive attitudes; the average score of protective behaviors was (11.07±1.40), and 73.6％of participants with positive protective behaviors. Spearman correlation analysis showed a weak correlation between knowledge and attitude (r=0.183, P< 0.001), a strong correlation between knowledge and behavior (r=0.770, P< 0.05), and a weak correlation between behavior and attitude (r=0.23, P< 0.001). Binary logistic analysis showed that knowledge (good vs. less:OR=1.515, 95％ CI:1.072-2.140; P<0.05) and attitude (supportive vs. non-supportive:OR=1.635,95％ CI:1.154-2.316; P<0.05) were related to protective behavior of COVID-19. The major channels of acquiring COVID-19 related information were social software (80.0％), social platform (69.9％), TV (67.0％), and website (65.4％) respectively. Conclusions:During the high epidemic period of COVID-19, KAP status of Hainan mobile phone users were generally not good. Health education of COVID-19 should target the low educated groups by using new media.