The invention discloses a warning fence for an injection molding machine operation chamber. The warning fence comprises a fixed seat and a fixed block, wherein a plurality of level holes are formed in a side wall of the fixed seat; a mounting block is arranged at the bottom of the fixed block; a first planar bearing and a second planar bearing are arranged on the side wall of the fixed block; a first abutting joint shaft is arranged between the fixed seat and the fixed block; the first abutting joint shaft penetrates through the first planar bearing; a second abutting joint shaft is arranged between the fixed seat and the fixed block; the second abutting joint shaft penetrates through the first planar bearing; a abutting joint rod is arranged between the fixed seat and the mounting block; a buffer spring is arranged on the peripheral surface of the abutting joint rod in a sleeving manner; a limiting ring is arranged at the outer end of the abutting joint rod; the limiting ring is arranged on the outer side wall of the fixed seat; a mounting slot and a locking shaft are arranged at the end part of the fixed block; a protective plate is arranged at the mounting slot; one end of the protective plate is arranged on the locking shaft in a sleeving manner, and the other end of the protective plate is a free end. The warning fence can be mounted outside the injection molding machine operation chamber, and can achieve a warning effect through the protective plate.