Abstract: Based on the ultimate strength surface of concrete under multiaxial stress and the Willam-Warnke five parameter failure criterion, a deterministic model for the peak stress of concrete confined by ties was established by combining with 144 groups of test data of prism concrete specimens confined by ties. Then, taking into account the influence of both epistemic and aleatory uncertainties, a probabilistic model for the peak stress of concrete confined by ties was established by the Bayesian theory and the Markov chain Monte Carlo method. The accuracy and applicability of the model were validated by comparing with the experimental data and the traditional deterministic models. The analysis results show that the proposed probabilistic model can reasonably describe the probabilistic characteristics of the peak stress of concrete confined by ties, since it can not only calibrate the confidence level and accuracy of existing deterministic models, but also determine the probabilistic characteristic value of the peak stress of concrete confined by ties corresponding to the predefined confidence level.