Grade I: (Immediately) with life-threatening illnesses and injuries, should be assigned to resuscitation room by green channel immediately;
Grade II: (<10 mins) with potential life-threatening illnesses and injuries or dramatic change in conditions, emergency treatment and close observation are required;
Grade III: (<30 mins) with serious illnesses or injuries but with stable vital signs or with acute symptoms not relieved;
Grade IV: (<60 mins) with acute illnesses or injuries but not exacerbate, with stable vital signs, waiting is acceptable;
Grade V: (<120 mins）with stable situation and not exacerbate, should wait for physicians.