Objective. To explore the effects of modified Jianpi Qushi Heluo decoction on scores of TCM syndromes, 24 h urinary albumin (UA), and plasma albumin (Alb) in idiopathic membranous nephropathy (IMN) of spleen-kidney qi deficiency. Methods. A total of 84 patients with IMN of spleen-kidney qi deficiency type admitted to the hospital were enrolled between November 2019 and September 2021. According to the random number table method, they were divided into the observation group (42 cases) and control group (42 cases). The control group was treated with routine Western medicine, while the observation group was additionally treated with modified Jianpi Qushi Heluo decoction. All were continuously treated for 2 months. The clinical curative effect between the two groups was compared. Before and after treatment, scores of TCM syndromes, biochemical indexes (24 h UA, plasma Alb, serum triglyceride (TG), and serum cholesterol (TC)), and T lymphocyte subsets (Th1, Th2, Th1/Th2, and Th17) were compared between the two groups. The occurrence of adverse reactions in both groups during treatment was recorded. Results. The difference in the total response rate of treatment between the observation group and control group was not statistically significant (90.48% vs. 73.81%) ( P > 0.05 ). After 2 months of treatment, scores of TCM syndromes in the observation group were significantly lower than those in the control group, levels of 24 h UA, TG, and TC were significantly lower than those in the control group, and Alb was significantly higher than that in the control group ( P < 0.05 ). After 2 months of treatment, levels of peripheral blood Th1 and Th17 in the observation group were significantly lower than those in the control group, while Th2 and Th1/Th2 were higher than those in the control group ( P < 0.05 ). The difference in incidence of adverse reactions between the observation group and control group was not statistically significant (4.76% vs. 14.29%) ( P > 0.05 ). Conclusion. The modified Jianpi Qushi Heluo decoction can reduce UA, increase Alb, and improve clinical symptoms and immune function of patients with IMN of spleen-kidney qi deficiency.