Objective To analyze the influence of vasoactive drugs on hemodynamics in septic shock patients and to explore the guiding value of systemic vascular resistance index (SVRI) for the application of vasoactive drugs .Methods 21 cases of septic shock in ICU from March 2010 to April 2012 were retrospectively analyzed .The PiCCO monitor technique was applied to monitor the he-modynamic parameters including the cardiac index (CI) ,intrathoracic blood volume index (ITBI) ,systemic cenous resistance index (SVRI) and mean arterial pressure(MAP) ,once per 6-8 h .ITBI>850 mL/m2 was taken as the normal criterion .The data of 202 cases meeting the criterion were collected .These cases were divided into two groups according to whether MAP reach 65 mm Hg , the differences of hemodynamic parameters between the two groups were compared .The MAP≥65 mm Hg group was redivided in-to the group 1 ,2 and 3 according to SVRI .Blood characteristics of pressure ,CI and ITBI were compared among these 3 groups .Re-sults The ITBI value in the MAP<65 mm Hg group and the MAP≥65 mm Hg group was higher than the normal value .The CI and SVRI values in the MAP≥65 mm Hg group were higher than those in the MAP< 65 mm Hg group(P<0 .05) ,while the ITBI value had no difference between the two groups .The ITBI values in the three groups with different SVRI all were higher than the upper normal limit ,furthermore ,in the comparisons among 3 groups ,only comparison between the group 1 and the group 3 had sta-tistical difference(P= 0 .47) .When SVRI was lower ,the CI value was higher than the normal value .Along with the increase of SVRI ,MAP increased gradually ,and CI gradually declined .When SVRI was too high ,MAP had no significant increase ,but the CI value was lower than the lower limit .Conclusion The SVRI monitoring by PiCCO can help to guide the application of vasoactive drugs in septic shock patients ,lower SVRI means the declined vascular reaction and higher SVRI indicates the low cardiac function , moreover blood pressure can not be further enhanced by vascular excessive contraction .