Summary: Background: Breastfeeding is essential for the growth and development of all infants. Despite the large transgender and gender-diverse population size, there is no comprehensive research of breastfeeding or chestfeeding practices in this group. This study was designed aimed to investigate the status of breastfeeding or chestfeeding practices in transgender and gender-diverse parents and to explore the possible influencing factors. Methods: A cross-sectional study was conducted between January 27 2022 and February 15 2022 online in China. A representative sample of 647 transgender and gender-diverse parents was enrolled. Validated questionnaires were used to investigate breastfeeding or chestfeeding practices and its associated factors, including physical factors, psychological factors and socio-environmental factors. Findings: The exclusive breastfeeding or chestfeeding rate was 33.5% (214) and only 41.3% (244) of infants could be continuously fed until 6 months. Accepting hormonotherapy after having this child (adjusted odds ratio (AOR) = 1.664, 95% confidential interval (CI) = 1.014∼2.738) and receiving feeding education (AOR = 2.161, 95% CI = 1.363∼3.508) were associated with a higher exclusive breastfeeding or chestfeeding rate, while higher gender dysphoria scores (37–47: AOR = 0.549, 95% CI = 0.364∼0.827; >47: AOR = 0.474, 95% CI = 0.286∼0.778), experiencing family violence (15–35: AOR = 0.388, 95% CI = 0.257∼0.583; >35: AOR = 0.335; 95% CI = 0.203∼0.545), experiencing partner violence (≥30: AOR = 0.541, 95% CI = 0.334∼0.867), using artificial insemination (AOR = 0.269, 95% CI = 0.12∼0.541), or surrogacy (AOR = 0.406, 95% CI = 0.199∼0.776) and being discriminated against during seeking of childbearing health care (AOR = 0.402, 95% CI = 0.28∼0.576), are significantly associated with a lower exclusive breastfeeding or chestfeeding rate. Participants who had feeding education were more likely to feed their child with human milk as the first food intake (AOR = 1.644, 95% CI = 1.015∼2.632), while those who had suffered from family violence (>35: AOR = 0.47; 95% CI = 0.259∼0.84), discrimination (AOR = 0.457, 95% CI = 0.284∼0.721) and chose artificial insemination (AOR = 0.304, 95% CI = 0.168∼0.56) or surrogacy (AOR = 0.264, 95% CI = 0.144∼0.489), were less likely to give their child human milk as first food intake. Besides, discrimination is also related to a shorter breastfeeding or chestfeeding duration (AOR = 0.535, 95% CI = 0.375∼0.761). Interpretation: Breastfeeding or chestfeeding are neglected health problems in the transgender and gender-diverse population and many socio-demographic factors, transgender and gender-diverse-related factors, and family environment are correlated with it. Better social and family support is necessary to improve breastfeeding or chestfeeding practices. Funding: There are no funding sources to declare.