The invention relates to the technical field of clamping devices, and discloses a clamping device for machining aluminum shell of a power battery. The clamping device for processing the aluminum shell of the power battery comprises a base, a fixing plate is fixedly installed in the center of the upper surface of the base; a fixing table is fixedly installed at the top part of the fixing plate, and supports are fixedly installed at the two ends of the upper surface of the base; connecting plates are fixedly installed at the opposite faces of the two supports, and telescopic rods are fixedly connected with the top ends and the bottom ends of the opposite faces of the two connecting plates; and surfaces of the telescopic rods are sleeved with telescopic springs. According to the clamping device for processing aluminum shell of the power battery, by arranging the fixing table and a lower pressing plate, the fixing table is fixed to the lower surface of the aluminum shell, and the lower pressing plate is driven by a rotating screw rod to carry lift motion in the vertical direction, the upper surface of the aluminum shell can be fixed, the fixing effect of the clamping device is further improved, so that machining efficiency of the aluminum shell of the power battery is improved, and practicability of the clamping device for machining the aluminum shell of the power battery is enhanced.