Outpatient satisfaction is important in evaluating the performance of tertiary public hospitals in China. However, only a few studies have examined the interaction between outpatient satisfaction and its related factors. This study aimed to explore the relationship between patient satisfaction and its related factors in provincial tertiary hospitals. Six hundred outpatients in three provincial tertiary hospitals in Nanchang, China, were randomly selected. Structural equation modeling was used to analyze the relationship of the factors associated with outpatient satisfaction. The conceptual model fitted the data well (χ²/df = 4.367, CFI = 0.951, TLI = 0.937, SRMR = 0.055, RMSEA = 0.075), with all the path coefficients being statistically significant (p < 0.001). The environment and facilities showed the most significant influence on outpatient satisfaction (standardized total effect = 0.389), followed by the quality of diagnosis and treatment (standardized total effect = 0.235). The waiting time for medical services showed a partial mediation effect of 0.077 between the environment and facilities and outpatient satisfaction. The study indicates that targeted measures should be taken to improve the amenities of hospitals and shorten the waiting time for medical services, thus further improving outpatients’ medical experience.