The invention relates to an assembly type foundation pit supporting structure using grouting bolts. The supporting structure comprises box type component standard parts and is characterized in that grouting bolt holes are formed in the box type component standard parts in an allowance mode when prefabricating, the standard parts are connected with soil body by the grouting bolts through the bolt holes, the grouting bolts can provide tensile force to supporting walls when the supporting walls formed by the box type parts have a lateral displacement tendency, a hollow rectangular steel tube inner support is arranged, the steel tube inner support is connected with the box type parts by utilizing the existing bolt holes, a horizontal support is provided to the supporting walls formed by the box type component standard parts, and the foundation pit supporting structure is formed by the grouting bolts and the free combination of the steel tube inner support. The grouting bolts are assembly types, and are formed by fixedly connecting screw nut ends, one to several standard section bolt rods and bolt tips in sequence, the lengths of the whole grouting bolts are changed according to the number of standard section bolt rods, the standard section bolt rods are full and hollow, and the grouting holes are formed in the axial direction.