This study aims to observe the effects of testosterone replacement therapy on glucose and lipid metabolism in middle-aged and elderly high-fat-fed male rats. This study established a high-fat-fed rat model and supplemented the rats with different doses of testosterone after castration. The rats were divided into control, complete lack of testosterone, low testosterone, medium testosterone, and high testosterone groups. Peripheral blood testosterone, blood lipid, blood glucose, and insulin levels were measured and the livers stained. Total Cholesterol (TC) and Low-Density Lipoprotein Cholesterol (LDL-C) levels in the low testosterone and complete lack of testosterone groups were higher than those in the control group (P<0.05); TC and LDL-C in the high and medium testosterone groups were less than those in the complete lack of testosterone group (P<0.05). There were no significant differences in blood glucose and insulin levels between groups (P>0.05). The groups, in increasing order of degree of liver steatosis, were the high testosterone, control, medium testosterone, low testosterone, and complete lack of testosterone groups. Visible fibrosis was observed only in the complete lack of testosterone, low testosterone, and medium testosterone groups. Testosterone can regulate peripheral blood TC and LDLC levels in middle-aged and elderly male rats, and testosterone deficiency can aggravate liver ectopic fat deposition.