This work aimed to evaluate the paste stability and desizability of new starch grafted copolymer [poly(sodium allylsulfonate)-g-starch-g-poly(ethyl acrylate)] (PSAS-g-starch-g-PEA) for providing an important supporting role in sizingapplication. The PSAS-g-starch-g-PEA samples were prepared by grafting reaction of acid-thinned starch (AHS) with SASand subsequent with EA in water phase. The PSAS-g-starch-g-PEA granules were characterized by Fourier transforminfrared spectroscopy and scanning electron microscopy. Also, paste stability was assessed and desizability was investigatedin terms of desizing efficiency, swelling ability of the film and time interval for the break of starch film in water. Comparedwith control AHS, the PSAS-g-starch-g-PEA had higher paste stability, desizing efficiency and swelling ability, and lowertime interval required, concluding that the PSAS and PEA branches could promote the paste stability and desizability ofstarch. Increasing the number of both branches facilitated the paste stability and desizability. PSAS-g-starch-g-PEA displayedpotential value in textile sizing field.