Objective To measure the indexes of biological characteristics of organ weight and organ coefficient of SPF BALB/c nude mice.Methods 38 SPF BALB/c nude mice(19 males and 19 females) were chosen,and the body weight and 12 organs' weight were determined,then the organ coefficients were counted.Results Between female and male nude mice,the kidney weight and brain weight showed significant difference(P<0.01) and the difference of weight,heart,liver,adrenal gland weight was obvious(P<0.05),the coefficient of brain,adrenal gland had remarkably significant difference(P<0.01) and the coefficient of kidney was obvious(P<0.05).Linear analysis showed that there were obvious linear relations between body mass with heart,liver,kidney,brain,adrenal gland and testicle in male mice;there were linear relations between body weight and liver,kidney,and stomach in female mice.Conclusion Differences existed in weight,heart weight,liver weight,kidney weight,brain weight,adrenal gland weight,coefficients of kidney,brain,and adrenal gland between female and male nude mice,and there had linear relationships between body weight and organs.