Swelling of anhydrite rock is a major threat in tunneling engineering, causing serious damage to tunnels as well as producing high additional costs during tunnel construction and operation. Reliable prediction of swelling pressures and deformations based on conventional swelling constitutive models is extremely difficult. This paper focuses on developing a practical swelling constitutive model of anhydrite for tunnel engineering. Firstly, swelling tests of natural anhydrite samples, focusing on time effect, were designed and conducted. The test results show swelling strain-time can be better described by S-curve model, and swelling stress-strain can be better described by quadratic model. Secondly, a swelling constitutive model with consideration of time effect was developed to reproduce the swelling behavior of anhydrite observed in swelling tests. This model can track the evolution of swelling activity in the tunnelling, which has practical significance for process simulation and process control of swelling disaster. Then this model was implemented within ANSYS for numerical simulation of Lirang tunnel. Based on simulation results, some useful measures were proposed and applied to this tunnel, and got a satisfactory result according to the on-site feedback information.