Objective To explore the characteristics and differences in weight management among breast cancer patients during chemotherapy, so as to provide guidance for weight management or developing applications for breast cancer patients. Methods A total of 16 breast cancer patients were selected using purposive sampling, and semi-structured deep interview were conducted to obtain their personal attributes, mobile device usage and weight management, which were analyzed using Colaizzi′s seven step analysis method. The specific process is as follows:primary information, fact labels, model dimensions construction. Then the participants′ characteristics were manually extracted, and the visualization of the user persona was completed by pictures and user labels. Results Four dimensions of weight management among breast cancer patients during chemotherapy were extracted:cognition of weight management, chemotherapy symptoms and emotion, lifestyle changes and sources of information, which were combined with individual preference and internet use habit to construct 5 typical user personas of weight management: active weight manager, fatigue and non-exerciser, young patient with serious lack of knowledge, overweighter taking treatment as priority, irregular exerciser with a little understanding of weight management. Conclusion The cognition and behavior of weight management among different chemotherapy breast cancer patients are significantly different. It is suggested to depict the user persona before designing weight management programme or mobile health platforms, thus, targeted intervention can be developed and implemented precisely.