Dispersive saline soil is a type of water sensitive special soil with the characteristic of instability when encountering water, and its engineering properties are unstable. Therefore, this research proposes the use of environmentally friendly biopolymer guar gum to improve soil dispersivity and explores the feasibility of guar gum in improvement of dispersive saline soil. The mechanical properties of the improved dispersive saline soil were determined through unconfined compressive strength tests and direct shear tests. The influence of guar gum on the dispersivity and physical properties of the soil were investigated by crumb tests, pinhole tests, liquid plastic limit tests and particle size distribution tests. The microstructure and mineral composition of the improved soil were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy tests. Experimental results indicate that 1.5 % guar gum can transform highly dispersive soil into non-dispersive soil after curing 28 days. When the guar gum content increases from 0 % to 4 %, the unconfined compressive strength increases by 81.30 %, and the cohesion and internal friction angle increase by 117.02 % and 32.69 %, respectively. Guar gum is enriched with hydroxyl groups, which form hydrogels in contact with water, and form a cationic bridge with the surface cations of clay particles, the two aspects work together to cement the soil particles, dense soil structure. Guar gum can effectively improve the dispersivity and mechanical properties of dispersive saline soil, and can be used as an environmentally friendly soil modification material.