Abstract: The constitutive equation of thixotropic fluid was of the Moore'smodel in this paper. The mechanical behaviors under oscillatory loadingwere discussed. The finite difference method was used. The results show that: 1) In the steady state, the parameter whichdescribed the internal structural state in the fluid was the periodicfunction of time; 2) The relation between the stress and the strain was aclosed hysteretic cycle. These properties show that the thixotropicfluid is much more complex than the other non-Newtonian fluids.