Nanocellulose has attracted attention due to its renewable and biodegradable properties, coupled with its outstanding physicochemical characteristics. However, owing to production methods, challenges in redispersing after drying, and other issues, nanocellulose is still mainly produced, transported, stored, and applied in the form of aqueous suspension. Concurrently, the nanocellulose suspension exhibits unique rheological behaviors such as viscoelasticity, thixotropy, yield stress and distinctive nonlinear stress response. They possess properties including thickening, emulsification, gel, stability, adhesion, adsorption and other properties, and has important applications in food, cosmetics, medical and energy fields. Moreover, it was found that a small amount of polysaccharide solution could induce the gelation and formation of liquid crystal structure of dilute rod-like cellulose nanocrystalline (CNC) suspension. This study employed SEM, AFM, FT-IR, XRD, and other characterization techniques to thoroughly analyze the structure of CNC particles. Subsequently, the thixotropy and yield behavior of its suspensions were analyzed using methods such as hysteresis loop, three-stage thixotropic recovery test, creep and stress bifurcation. The nonlinear response was analyzed using large amplitude oscillatory shear (LAOS) methods such as Fourier transform rheology, stress decomposition, Chebyshev polynomials, and sequence physical processes. Finally, the interface interaction, phase behavior, and macroscopic rheological properties of CNC with polysaccharides were investigated by techniques such as dissipative quartz crystal microbalance and polarizing microscope. The phase behaviour and rheological properties of CNC suspensions exhibit strong concentration dependence. CNC particles with an average aspect ratio of 26 begin to orientate and form liquid crystals at a concentration of 4.50 wt%, with the liquid-solid transition occurring at 4.96 wt%. Their yield behaviour demonstrates multi-stage changes and exhibits a degree of ductility. Nonlinear viscoelastic parameters indicate that the suspension exhibits intra-cycle strain hardening and shear thickening behaviour under medium-amplitude oscillatory shear (MAOS). The widest range of intra-cycle rheological transitions correlates with a sharp increase in dissipation rate and weak strain overshoot behaviour. Guar gum, characterised by high molecular weight and random coil conformation, exhibits typical solution rheological behaviour. It adsorbs onto CNC particles, substantially increasing the hydrodynamic size and effective volume fraction of CNC. This facilitates the formation of anisotropic structures and efficient synergistic thickening and gelation at low CNC concentrations. Notably, guar gum solutions at 0.05 wt%, 0.1 wt% and 0.5 wt% respectively induce liquid-solid transition, phase transition and the formation of a self-supporting gel in a 3.0 wt% CNC suspension. The resulting gel exhibits high viscoelasticity, yield stress, and yield strain (620%), with transient rheological transitions during the cycle comprising four distinct physical processes: viscoplastic deformation, structural recovery, early yield, and late yield. This systematic and comprehensive investigation into the rheological properties of cellulose nanocrystal suspensions and their synergistic thickening systems with polysaccharides provides a theoretical foundation for their broad application in food, coatings, cosmetics, lubricants, and household formulation products.