The invention discloses a convenient and fast forming disc of a straw pressing machine. The convenient and fast forming disc comprises a main disc body and an auxiliary disc body. According to the convenient and fast forming disc, first through holes are formed in the main disc body, a first butt-joint part is arranged on one side of each first through hole, second through holes are formed in theauxiliary disc body, a second butt-joint part is arranged on one side of each second through hole, and the structures of the first butt-joint parts and the second butt-joint parts are set, so that thefirst butt-joint part and the second butt-joint part can be matched to form a discharging hole when the auxiliary disc body is fixed with the main disc body; during the use process, the auxiliary disc body can be dismounted from the main disc body when the discharging hole is blocked, so that the first butt-joint parts and the second butt-joint parts can be correspondingly pulled away from the second through holes and the first through holes, the discharging hole can be divided into two open arc-shaped grooves, a blocking material can be easily removed by working personnel, and the inner wallof the discharging hole can be protected against damage; and the convenient and fast forming disc is simple in structure, convenient and fast.