BACKGROUND: Antimullerian hormone, the most reliable biomarker of ovarian reserve, is widely used in various clinical situations. Antimullerian hormone levels consistently decrease with age. However, there is no standard, age-specific reference values for antimullerian hormone in women of reproductive age, which limits its application. OBJECTIVE: This study aimed to establish age-specific antimullerian hormone percentile reference values for women of reproductive age. STUDY DESIGN: A nationwide, population-based cross-sectional survey was conducted between May 2019 and April 2021 in 15 provinces and municipalities in mainland China. A total of 10,053 eligible women aged 20 to 49 years were selected using a multistage stratified sampling procedure. Women who were pregnant, had undergone ovarian surgery, took hormone drugs in the past 3 months, or had an antimullerian hormone outlier value were excluded from establishing antimullerian hormone percentile reference values. Serum antimullerian hormone concentrations were measured using ultrasensitive, 2-site enzyme-linked immunosorbent assays (Ansh Lab, Webster, TX) in the Reproductive Endocrinology Laboratory of Peking University Third Hospital. Generalized additive models for location scale and shape with the Box-Cox t original distribution were used to estimate the fitted antimullerian hormone percentile reference values. RESULTS: A total of 9112 eligible women aged 21 to 49 years were included in the fitting model. The fitted 50th (2.5th-97.5th) percentiles of antimullerian hormone values for women aged 21, 25, 30, 35, 40, 45, and 49 years were 4.83 (0.79-18.41), 4.47 (0.72-16.58), 3.67 (0.50-13.82), 2.59 (0.24-10.35), 1.35 (0.05-6.68), 0.33 (<0.01 to 3.40), and 0.04 (<0.01 to 1.77) ng/mL, respectively. The populationbased decline rate of antimullerian hormone accelerated with increasing age, especially age >35 years. The magnitude of the decline of the 25th antimullerian hormone percentile curve was greater than that of the 75th percentile curve. CONCLUSION: This study established age-specific antimullerian hormone percentile reference values for women of reproductive age based on a large representative sample of the general population and described antimullerian hormone changes. These findings may facilitate antimullerian hormone application in clinical practices.