The Fenhe River-Weihe River Basin is one of the areas with the most developed ground fissures and related geohazards in China and even in the world. The effect of the rheological properties of loess during the long geological history is considered as the fracture extension mode of ground fissures. Applying stepwise loading and cyclic unloading, a series of consolidated undrained triaxial tests is conducted on Q3 intact loess sampled from Chang'an ground fissures belt in Xi'an region, to examine the rheological properties of the loess with different confining pressures. The loading and unloading creep curves, strain rate vs. time curves of Q3 intact loess within ground fissures are obtained. The experimental results show that the Q3 intact loess is featured with slow creep under low stress and slow creep or constant creep under high stress. Based on the unified rheological theory, a three-dimensional creep constitutive model which is suitable for Q3 intact loess within ground fissures belt in Xi'an region is established; and parameters of the model are obtained. The results lay a foundation for studying the fracture extension model of concealed ground fissures and the mechanism behind.