At a time when the population is aging and the digital divide among older adults is becoming increasingly prominent, the research on the smartphone use behavior of the older adult in China is slightly insufficient. Therefore, this study aims to develop a smartphone acceptance model for older adults in China to predict the factors of their behavioral intention to use smartphones. Using Stimulus-organism-response (SOR) theory as the framework, planned behavior theory, self-efficacy theory and technology acceptance model as the theoretical basis, and employed a mixed quantitative and qualitative research approach to analyze the data from 244 older adults using structural equation modeling. The results show that technology anxiety, subjective norms, self-efficacy, perceived usefulness, facilitating conditions, and perceived ease of use had significant effects on the behavioral intention smartphones among older adults. In addition, perceived usefulness was directly influenced by subjective norms and perceived ease of use, facilitating conditions significantly influenced perceived ease of use and self-efficacy, and subjective norms and self-efficacy significantly affect technology anxiety. This study expanded the applicability of SOR framework, further expanded the technology acceptance model, and enriched the theory of smart phone use behavior of older adults users. The results of this study provide a valuable theoretical framework for the study on older adults users’ behaviors and have implications for the design and marketing of smartphones with high acceptancy from older adults.