Abstract: A portable flexible air pump comprises a connection head, a main body and a flexible body located between the connection head and the main body. The connection head is provided therein with an air duct and is engageable with the air valve of a bicycle tire. The main body is provided therein with an air channel in communication with the air duct of the connection head. The air channel is intended to transmit the compressed air. The flexible body is provided axially with a passageway and is connected at both ends thereof with the connection head and the main body by two pivoting members. The air duct of the connection head is in communication with the air channel of the main body via the passageway of the flexible body. The connecting portion between the flexible body and the connection head and the connecting portion between the flexible body and the main body are made airtight by two leakproof portions.