The invention discloses a starch-based multi-channel airflow unit and a preparation method and an application thereof. The preparation method of the present invention comprises the following steps: melting a polylactic acid, wherein a temperature of a first temperature control zone is 135° C. to 145° C., a temperature of a second temperature control zone is 175° C. to 185° C., a temperature of a third temperature control zone is 190° C. to 200° C., and a temperature of a fourth temperature control zone is 175° C. to 185° C.; gelatinizing a starch-based material, adding the starch-based material in the third temperature control zone and fully mixing the mixture; adding a polyol in the third temperature control zone, and fully mixing the mixture; and extruding out the mixed material through twin screws, sizing in vacuum, cooling and sizing, and winding and cutting to obtain the starch-based multi-channel airflow unit.