The risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to maternal and newborn health has yet to be determined. Several studies on influenza have shown an increased risk of maternal morbidity and mortality, especially during pregnancy and lactation, including those infected with SARS-CoV-2. This has the risk of increasing maternal anxiety during the pandemic. Psychological effects, severe stressors for breastfeeding mothers can cause disruptions to the lactation process as well as to baby care. This study aims to examine the effect of the level of knowledge and anxiety of breastfeeding mothers on the lactation process during the COVID-19 pandemic. The method used is quantitative with a retrospective analytic approach. The populations in this study were mothers who had children aged 0 to 2 years. The sampling technique was done by purposive sampling and obtained a large sample of 46 mothers. The instruments used in this study were a questionnaire on maternal knowledge about the corona virus and its prevention efforts which have been tested for validity by researchers, an anxiety questionnaire modifying the HARS (Hamilton Anxiety Rating Scale) and a check list for the implementation of the lactation process. Data collection was carried out by distributing Google forms via WhatsApp groups to eight-village toddler classes in the Pekalongan Regency area. The study showed that mothers who had less education had a 1.89 times higher risk of obstacles in the breastfeeding process (p-value: 0.458; CI: 0.294-21.034) while mothers who had severe anxiety had 3.34 times the risk of inhibition in the breastfeeding process ( p-value: 0.0677; CI: 0.054-0.333). The conclusion is knowledge and Anxiety of breastfeeding mothers affect the lactation process. The role of health workers in providing accurate and fast information during a pandemic is very significant in reducing anxiety levels and increasing maternal knowledge.