Complex distillation systems, such as extractive distillation systems and thermally coupled distillation systems have important applications in chemical industry. However, simultaneous optimization of all the variables in these systems with the rigorous MESH model is still difficult because of both the convergence problem and integer optimization problem. In this work, based on the pseudo-transient continuation (PTC) approach, a simple and robust PTC distillation model was developed in the equation-oriented (EO) environment. It was based on the dynamic simulation but with a pseudo-hold-up correlation, which resulted in a well-posed and easily solved differential algebraic equation (DAE) system. Then, three optimization cases were studied to validate the performance of the bypass efficiency method and the new PTC model.