【Objective】 To observe changes of microcirculation and blood coagulation when blood pressure in dangerously ill newborn was high and to provide evidence for treatment. 【Methods】 30 newborn children with high blood pressure were chosen, 30 cases were control group. External ear microcirculation in neonates by WX-10C microcirculation microscope, Determination of Serum prothrombin time (PT), Thrombin time (TT), Activated partial thromboplastin time (APTT), Fibrinogen were observed and compared the results between the two groups. 【Results】 The accumulated points about shape of microvessel and blood flow of microcirculation were increased. Discrepancy was significant (P<0.05). Serum prothrombin time (PT), Thrombin time (TT), Activated partial thromboplastin time (APTT) in group of high blood pressure were decline, Fibrinogen was increased (P<0.05). 【Conclusions】 There are disfunction of microcirculation and blood coagulation when blood pressure is high in dangerously ill newborn. Dealing with these disfunction at the same time is necessary while to treat primary disease and reduce blood pressure.