The present invention relates to a U-shaped dental impression tray comprising a first handle portion and a U-shaped impression material first accommodation portion, wherein the U-shaped impression material first accommodation portion comprises a first support having a curvature radius larger than the teeth, a second support having a curvature radius smaller than the teeth, a first net cloth provided between the first support and the second support, and first impression re-discharge holes which are respectively punctuated at one side of upper and lower portions of the curved surface of the first support or the curved surface of the second support around the first net cloth, and an extension portion symmetrically extended from the U-shaped center in the U-shaped impression material first accommodation portion is extended beyond the occlusal point of teeth. Additionally, the first impression re-discharge holes are formed in such a way that the cross-section of the hole formed on the outer surface of the first support or the second support is larger than that of the hole formed on the inner surface of the first support or the second support, and a plurality of the first impression re-discharge holes are formed in such a way that any one hole can be punctuated toward the upper portion of the first support or the second support and a hole adjacent to the hole can be punctuated toward the lower portion of the first support or the second support. Moreover, the present invention relates to the U-shaped dental impression tray comprising a second handle portion and a U-shaped impression material second accommodation portion, wherein the U-shaped impression material second accommodation portion comprises narrow U-shaped third supports formed so as to allow a row of teeth to come therein, a second net cloth provided between the third supports, and second impression re-discharge holes which are respectively punctuated at one side of upper and lower portions of the curved surface
