Public confidence on the warning message of unconventional emergency events is critical for emergency response and the minimum loss of life and property．Through a survey，differences of the warning effect of Web channels of unconventional emergencies information are compared．Based on organizational trust integration models and researches about media credibility，a conceptual model of web media credibility is proposed and estimated by means of structural equation modeling with partial least square method．The findings show that the significant factors of credibility are different for the channels．The result provides implications for unconventional emergency events information dissemination．