In today's world, tourism has gradually become a rapidly growing and huge industry. The tourism industry plays an increasingly important role in stimulating urban economy, promoting social employment, and improving culture and environment. This paper aimed to study the evaluation technology of tourism environmental capacity of natural reserves based on big data analysis. In this paper, a mathematical model of tourism environmental capacity was proposed. Based on this study, the tourism environmental capacity experiment of Nature Reserve A based on big data analysis was analyzed. The experimental results of this paper showed that the annual tourism space capacity of Nature Reserve A was about 470000 person-times, and through the questionnaire survey, it was found that the tourism psychological capacity of Nature Reserve A was about 1300 people per day. In tourism development, strengthening environmental protection can effectively increase tourism environmental capacity.