Abstract: At present, the widely used polymer materials and bentonite mud are difficult to degrade and cause environmental pollution. In this study, natural thickeners of the agar and guar gum are used to produce new mud instead of the traditional macromolecule materials, and the film forming effects of the new mud in sandy stratum are explored. The results show that the agar gum and the guar gum have better thickening effects and filtration loss reduction effects, and the colloidal rate is easier to increase to 100%. Compared with the traditional thickener CMC, the guar gum has stronger thickening effects. The agar and guar gum can change the mud from non film-forming into permeable zone mud film, promote the mud film-forming in the stratum, reduce the early filtration amount and permeability coefficient of mud film in the process of formation permeability and film-forming, and then reduce the total filtration amount in the stratum, Therefore, they can be used as a new type of natural mud additive.