Abstract： Objective To explore the correlations of biochemical factors as gamma-aminobutyric acid (GABA) level with amino acid metabolism level in the blood, levels of intestinal immunoglobulin A (IgA)+complement factor 3 (C3), feeding intolerance and fatiguability in children with hypotonia cerebral palsy. Methods Ninety-six children with hypotonia cerebral palsy,admitted to our hospital from January 2009 to January 2012,were chosen in our study; questionnaire was used to understand the clinical symptoms of the children; the blood ammonia level,hepatic function and IgA+C3 level were obtained from routine blood chemistry testing, and amino acid metabolism was detected by blood tandem mass spectrometry; the correlations of GABA level with amino acid metabolism level in the blood, levels of IgA+C3, feeding intolerance and fatiguability were statistically analyzed. Results In all the 96 children with hypotonia cerebral palsy,63 (65.63％) had low arginine; 52 had both decreased arginine and elevated blood ammonia levels, enjoying negative correlation (r=-0.776,P=0.000); 42 had decreased arginine and reduced levels of IgA+C3 enjoying positive correlation (r=0.351,P=0.000); both decreased arginine level and feeding intolerance were noted in 47 with positive correlation (r=0.372,P=0.000).In these 96 children,30 (31.25％) had carnitine metabolism abnormality,including decreased propionyl carnitine/free carnitine or propionyl carnitine/acetylcarnitine levels in 21 (21.88％),increased hydroxyl palmitoyl carnitine/hydroxyl Palm enoyl carnitine level in 9 (9.37％),and decreased cysteine content in 3 (3.12％). Conclusion Metabolic abnormalities of arginine,carnitine and cysteine are noted in children with hypotonia cerebral palsy; a lot of exercise will consume arginine,carnitine and cysteine,which causes fatigue; children with low blood arginine content might also have increased blood ammonia level,reduced IgA+C3 level,trends of vomiting,susceptibility to infection and feeding difficulties,and therefore,children's mental state,immune function and exercise tolerance ability are affected.