Abstract: A novel rotational damper named torsional steel-tube damper is proposed, which can be implemented to the beam-column connection with energy dissipated in precast concrete structures. Five damper specimens with different parameters are designed and tested under quasi-static cyclic loading. Test results show that the specimens rotate around the pin shaft and have excellent rotational deformation. The limit angle is more than 0.06 rad, and the ductility factor is larger than 4.0 required by the specification. The hysteretic curves of the specimens are plump, and apparent isotropic hardening behaviour can be observed. The equivalent viscous damping factors of the specimens are about 0.5, indicating that the damper has good energy dissipation capacity. The specimen with a larger wall thickness and outer diameter and smaller effective tube length has larger rotational strength. Under cyclic loading with a constant amplitude, all fatigue performance parameters of the specimens are basically within the specification requirements of ±15%, and the specimen has good anti-fatigue performance. The modified Bouc-Wen model is introduced to simulate the cyclic behaviour of the damper, and the quantum particle swarm optimization algorithm is used to identify the model parameters. The identification results show that the modified Bouc-Wen model can well adapt to the specimens' isotropic hardening behaviour and has higher simulation accuracy than that of Bouc-Wen model. The modified model can be used for the seismic analysis of monolithic structures.