Abstract: Objective To investigate effects of fluid resuscitation under the guidance of pulse indicator continuous cardiac output (PICCO) on the immune function,inflammatory mediator and organ function in patients with septic shock. Methods Total 180 patients suffering from septic shock in ICU of our hospital from 2012 to 2015 were enrolled and divided into PICCO group (n=94) and conventional group (n=86).The fluid resuscitation procedure was performed in the PICCO group guided by PICCO for adjusting really time the hemodynamic parameters,and in the control evaluated by central venous pressure and vital signs.The vital signs,the level of ET-1,lactate and IL-10,T cells and microRNA-155 were compared between the two groups. Results There were no significant difference between the two groups in sex,age,APACHE Ⅱ scores,mean arterial pressure and state of shock (P>0.05).After the fluid resuscitation,the blood pressure fluctuations,levels of BNP,IL-10 and ET-1 of PICCO group were significantly lower than that in the conventional group (P<0.05).The microRNA-155 and T cells of PICCO group were significantly higher than those in the conventional group (P<0.05). Conclusion The liquid recovery under the guidance of PICCO can make blood pressure recovery smoothly,reduce cardiac load,decrease inflammation medium and improve immune function.