The invention discloses a filter automatic assembling device. The filter automatic assembling device comprises a rack (1), a filter film loading device (21), a bottom film loading device (22), a dual-layer thin film composite device (23), a dual-layer thin film stepping feeding device (24), a filter film punching pickup device (3), a filter conveying device (4), a filter welding device (5) and a filter discharging device (6), wherein the filter film loading device (21), the bottom film loading device (22), the dual-layer thin film composite device (23), the dual-layer thin film stepping feeding device (24), the filter film punching pickup device (3), the filter conveying device (4), the filter welding device (5) and the filter discharging device (6) are mounted on the rack. Through cooperative work of the above devices, assembling of a filter can be finished. Compared with the prior art, the filter automatic assembling device can automatically assemble the filter, punching, film suction and assembling can be coherent, the automation degree is high, sucked film deviating is prevented, the product assembling precision is high, sucking is carried out while cutting is carried out, andan obtained film is more complete and fit.