The invention discloses a structure for a disposable injector. The structure includes a turning portion, a connecting portion and a stopping portion connected in sequence. The turning portion can turn towards or backwards the stopping portion. The diameter of the turning portion is greater than that of the stopping portion, and the diameter of the connecting portion is smaller than those of the turning portion and the stopping portion. The length of the connecting portion, which indicates the distance between the turning portion and the stopping portion, is configured to allow the turning portion to contact with the edge of the stopping portion so as to stop the turning portion to rotate when the turning portion is disposed towards the stopping portion. In this case, a taper surface is formed, and the turning portion can still be rotated in the direction backwards the stopping portion. In addition, the present invention also discloses a disposable injector with this structure.
