The invention discloses a novel rocket projectile launch canister auxiliary supporting mechanism which comprises a supporting mechanism body, a sleeve spring, an adjustable locking mechanism and an auxiliary supporting base. The supporting mechanism body comprises a front swing frame, a rear swing frame, an arc supporting seat and an arc supporting plate, wherein the arc supporting plate is used for supporting a projectile body, the supporting mechanism body is of a four-connecting-frame structure, one end of the front swing frame and one end of the rear swing frame are movably connected with the auxiliary supporting base, the other end of the front swing frame and the other end of the rear swing frame are movably connected with the arc supporting seat, a convex block is arranged on the rear swing frame, and a limiting screw arranged on the auxiliary supporting base is in contact with the convex block and limits swing of the rear swing frame. The upper portion of the arc supporting seat is movably connected with the arc supporting plate, the front swing frame and the rear swing frame swing to drive the arc supporting plate to swing and further achieve switching between vertical projectile supporting performed by the arc supporting plate and horizontal projectile putdown. When the novel rocket projectile launch canister auxiliary supporting mechanism is stored and transported, the height of the auxiliary supporting base is adjusted to achieve self-adaptive reliable projectile front end supporting performed by the arc supporting plate, and vibration produced during transportation is effectively reduced.