Health-related quality of life (HRQoL) is an important consideration in managing patients. Spleen aminopeptide oral lyophilized powder (SAOLP) has been used to enhance cellular immunity in a patient. This multicenter, randomized, double-blind, placebo-controlled clinical trial was designed to evaluate the safety and efficacy of SAOLP for improving HRQoL in patients with breast cancer. Patients diagnosed with advanced breast cancer were included, and were administered SAOLP or placebo 4 mg qd for two cycles. The primary endpoint was improvement in HRQoL on day 42 measured by the EORTC QLQ-C30 and EORTC QLQ-BR23. Secondary endpoints included immunologic function, improvement in HRQoL on day 21 and 84, objective response rate, disease control rate, BMI and adverse events. On day 42, on the EORTC QLQ-C30 or EORTC QLQ-BR23, scores on the functional scales and QoL scale were significantly higher and scores on symptom scales were significantly lower in patients who received SAOLP compared to placebo (P < 0.05). On day 84, the number of CD3, CD4 and CD8 cells were significantly higher in patients who received SAOLP. There were no significant differences in objective response rate, disease control rate or BMI. SAOLP may improve HRQoL and the immune response in patients with advanced breast cancer, represents a convenient and safe adjuvant therapy.