Medication nonadherence is one of the most significant obstacles to tuberculosis (TB) control worldwide. Identification of the factors associated with medication nonadherence is important. However, few related studies have been carried out in Tibet. This study aimed to explore factors influencing medication nonadherence to pulmonary TB (PTB) treatment in Tibet, China, from the patient perspective. Patients and Methods: In this qualitative study, seventeen PTB patients in Tibet were recruited by purposive and maximum variation sampling methods. In-depth semistructured interviews were conducted to collect data on factors influencing medication nonadherence, and Colaizzi's seven-step method was used to analyze the data. Results: The medication nonadherence of PTB patients in Tibet was influenced by one or a combination of the following four factors. First, patient-related factors included a lack of knowledge of PTB treatment, poor self-management capability, poor self-regulation capability and misperception of health condition. Second, a medication-related factor was medication side effects. Third, health service-related factors included the poor treatment skills of doctors in primary hospitals and a lack of directly observed treatment (DOT). Last, sociocultural factors included the effect of traditional Tibetan medicine, lack of family member support and discrimination. Conclusion: Multiple interplaying factors influenced medication nonadherence during PTB treatment in Tibet, and the main influencing factors were a lack of knowledge about PTB treatment, poor self-management capability, and the effect of traditional Tibetan medicine. TB health workers in Tibet should provide permanently viewable PTB treatment knowledge materials to PTB patients when oral health education is conducted, find feasible alternative strategies to DOT and establish links to traditional Tibetan medicine hospitals.