Abstract: In order to improve the gelling behaviors of organic clay in mineral oil with low aromatic hydrocarbon content, several rheology modifiers are developed with different functional groups. A series of experiments are performed on mineral oil based drilling fluids to identify their general properties, low-shear rate viscosity, linear viscoelasticity and high temperature/high pressure rheology. It is shown that the mineral oil based drilling fluids containing rheology modifiers (e.g. polyester amide (BZ-ORM-Ⅰ), polyamidoamine (BZ-ORM-Ⅱ) and alkanolamine (BZ-ORM-Ⅲ)) present higher low-shear rate viscosity when the density is 1.30 g/cm³. The viscosities corresponding to shear rate of 1.7s^-1 and 0.17s^-1 meet the requirements of the ^“dynamic settling window^” theory and elastic modulus G^′is higher than viscous modulus G^″. An obvious synergistic effect occurs between polyamide amine and alkanolamine rheology modifiers, and yield values are higher in the situations of high temperature and high pressure or low shear rate. The rheology modifiers containing amide, amine and akloxy together are mainly used to realize excellent suspension properties and remain weak progressive gelling behaviors of mineral oil based drilling fluids by modifying their gelling structures.