The work aims to study the point trajectory at the bottom of adhesive coangle of auto end-lock box regarding the clamping stagnation and damage occurring at the bottom of adhesive coangle in the process of forming cuboid (square) auto end-lock box. The study was concentrated on the point trajectory in the 3D coordinates at the bottom of adhesive coangle in the process of forming cuboid (square) auto end-lock box, so as to determine locus equation of the parameters as sin curve. No matter whether the length and width of the cuboid were equal, the point trajectory at the bottom of adhesive coangle of the auto end-lock box was sin curve. The design of such sin curve can avoid clamping stagnation and damage occurring in the process of forming auto end-lock box and enable the design of the bottom of the auto end-lock adhesive box to be more rational.