An organic molecule of poly(propylene glycol) bis(2-aminopropyl ether) (ATPE) with electron-donating groups is blended with low-density polyethylene (LDPE) to prepare all-organic nonlinear resistive field grading material. Quantum chemical results show that ATPE has an electron-donating ability. Experimental results demonstrate that, compared with traditional inorganic SiC particles, ATPE reduces the LDPE composite's percolation threshold and improves the nonlinear conductivity, achieving much lower filler loading, which is attributed to the electron-donating groups of ATPE. In addition, ATPE also provides higher breakdown strength and surface flashover voltage as well as better toughness for LDPE composites than SiC particles. It provides the basis for high-performance all-organic nonlinear resistive field grading material.