A paper input mechanism having a buffer function and a printing device using the mechanism are disclosed. The paper input mechanism (300) includes a frame (1) forming a conveying passage (P) for conveying continuous paper, and further includes a fixed passage plate (4) and a buffer plate (2) both located at a paper inputting side of the conveying passage (P), wherein the buffer plate (2) has an initial position and is pressed by the continuous paper to deviate from the initial position; the buffer plate (2) is opposite to the fixed passage plate (4) when being located at the initial position, so as to form a paper input passage (R), and the paper input passage (R) is connected with the conveying passage (P). Arrangement of the buffer plate (2) not only implements the buffer function, but also results in close fit between the buffer plate (2) and the frame (1) of the paper input mechanism (300) to create a unique paper inputting port, thereby effectively avoiding the problem that continuous paper is incorrectly installed by a user, and improving the usability of the product.