Thinking of the biggest flow density to start an emergency in market

By analyzed the current domestic relevant norm and the design data of the biggest flow density,this paper put forward the correctly moment concerning the market start an emergency to meet an incident.That is by evacuation judgment the moment of biggest flow density attained in the market to make sure whether or not start the emergency.It can provide some thinking and methods for the market to decide whether or not start the emergency at high peak in holidays.