The invention discloses a method for crosslinking modification of a polyester nonwoven fabric with beta-sodium cyclodextrin alginate. The method includes the steps of firstly, pre-processing the polyester nonwoven fabric in a sodium hydroxide solution; secondly, grafting methacrylic acid, acrylamide, beta-cyclodextrin and sodium alginate, and conducting modification processing; finally, cleaning and drying the fabric. The method adopts chemical crosslinking grafting to modify the polyester nonwoven fabric, and the modified polyester nonwoven fabric has the grafted methacrylic acid, acrylamide, beta-cyclodextrin, sodium alginate and other components which can play the role of adsorbing heavy metal ions and cationic dyes. On the one hand, the unsaturated ions in the sodium alginate and copper ions undergo an ion exchange reaction, on the other hand, carboxyl and hydroxyl in the sodium alginate and the copper ions undergo chelation, so that the efficiency of removing the heavy metal ions is high. The absorbed heavy metal ions and cationic dyes are easy to elute, and the polyester nonwoven fabric can be used repeatedly, so that secondary pollution is not caused.