A portable detection system for allergic diseases includes a filtration-based inspection module and a reader module. The filtration-based inspection module includes an FPW sensor and a liquid sample filtration apparatus, wherein the liquid sample filtration apparatus includes an injection opening, a passage module, a filtering membrane and a gathering aperture. The injection opening is in communication with the gathering aperture. The FPW sensor comprises a frame body, a carrier and a sensing chip having an accommodating slot in communication with the gathering aperture. The carrier comprises a plurality of conductive terminals, and the conductive terminals are electrically connected with the sensing chip. The reader module comprises a connection slot capable of being inserted by the conductive terminals of the carrier.