Introduction:Advanced age is one of the primary risk factors for infertility. Poor ovarian response (POR) to exogenous gonadotropin is a prominent characteristic of advanced-age women undergoing in vitro fertilization and embryo transfer (IVF-ET), which results in fewer retrieved oocytes and poor pregnancy outcomes. Traditional Chinese medicine (TCM) has been shown to improve female fertility. Erzhi Tiangui (EZTG) formula, in the form of granules with 10 herbal ingredients, demonstrated potential benefits in improving oocyte and embryo quality and ovarian reserve. Thus, this study aims to evaluate the efficacy and safety of EZTG formula.Method:The study is a multicenter, double-blind, placebo-controlled, randomized controlled trial (RCT), which will be conducted at 10 reproductive centers of tertiary hospitals. This study will enroll 480 women with expected POR of advanced age (≥35 years old) who fulfill the 2011 Bologna criteria. Participants will be assigned to either the EZTG group or the placebo group at random in an equal ratio. Each individual will receive conventional IVF-ET with EZTG granules or placebo as a complementary treatment. The primary outcome is the number of oocytes retrieved. Adverse events and safety assessments will be also conducted.Discussion:This study aims to provide robust evidence of the efficacy and safety of EZTG formula as a complementary treatment for advanced-age women with expected POR undergoing IVF-ET.