The utility model relates to a quick-open envelope, which comprises a polygonal hollow bag body and a cover slip. The bag body is provided with a surface, an opening side forming the boundary of the surface and a plurality of sealing sides. The cover slip is connected with the bag body and used to seal the opening side. A tear line is arranged on the surface. The two ends of the tear line are bordered on the same or different sealing side. Through tearing the tear line, the area enclosed by the tear line can be opened to form an opening on the bag body. Through the opening, the receiver can take out the article in the envelope.