Objective To explore the effect of fish oil fat emulsion as perioperative nutritional support on patients with liver cirrhosis and portal hypertension.Methods Randomized controlled clinical trial was performed between September 2011 and September 2017 in patients with liver cirrhosis and portal hypertension who underwent pericardial devascularization and splenectomy.Hypocaloric total parenteral nutritional support (TPN) started from the first day after the operation for 5 consecutive days.Patients were divided into experimental group and control group according to thetype of fat emulsion used.43 patients in experimental group were applied for fish oil fat emulsion injection (10％ Omegaven) + medium long chain structure fat emulsion (20％STG) and 42 patients in control group were applied for medium long chain structure fat emulsion (20％STG).Liver function (total bilirubin and alanine aminotransferase),nutrition index (serum albumin and prealbumin),inflammatory mediators (TNF-α,IL-6 and IL-10) were measured before and after the operation,and the clinical outcomes were observed.Results There was no statistically significant difference in liver function and nutritional indices between the experimental group and the control group (P＞0.05).The inflammatory mediators like TNF-u,IL-6 and IL-10 on the first day after surgery were significantly higher than those before surgery in both groups [experiment group:(225.54±54.78) vs.(61.49±16.47),(74.94±6.36) vs.(39.84±2.77),(77.53±11.4) vs.(46.05±6.13) ng/L;control group:(229.26±62.15) vs.(63.48±13.76),(77.23±7.83)vs.(40.64±3.34),(73.89±7.97)vs.(44.88±5.72) ng/L;P＜ 0.01].With the progress of time,the proinflammatory factors like TNF-α and IL-6 decreased after the operation and the range of decrease was higher in experiment group than in control group [d4-d 1:(-56.88± 31.63) vs.(-35.96±20.02),(-13.52±5.20) vs.(-6.38±2.84) ng/L;d7-d1:(-150.67±42.58) vs.(-132.79±53.35),(-27.04±8.97) vs.(-20.85±6.38) ng/L;P＜ 0.05].The range of increase in anti-inflammatory media IL-10 was higher in experiment group than in the control group (d4-d1:(14.22±13.08) vs.(5.64±3.58) ng/L;d7-d1:(17.78±5.58) vs.(-37.96±11.43) ng/L;P＜0.05).The incidence of grade Ⅲ complications and total complications (4.7％ vs.21.4％,23.3％ vs.45.2％) and hospitalization time [(10.12 ±1.48) vs.(12.33±2.04) d] in the experimental group were significantly lower than those in the control group (P＜0.05).Conclusions In patients with liver cirrhosis and portal hypertension,perioperative nutritional support of fish oil fat emulsion can reduce systemic inflammatory response and operative complications and promote rapid recovery through its two-way regulation of inflammatory mediators.