The utility model discloses an apron for rectangular cell, which comprises a substrate, the centre of base plate is equipped with the relief valve, the both ends of base plate are equipped with positive terminal hole and the negative terminal hole that is used for passing positive terminal and negative terminal respectively, be equipped with the first square step, its characterized in that around the base plate lower surface: be equipped with the square step of second around the base plate upper surface, distance between the step face of the first square step and the step face of the square step of second is 0.1-0.5mm. The utility model discloses in welding process, avoided laser can pass the problem of the fit clearance of apron and casing inner chamber to the will not burns out the inside utmost point group of battery, influences the qualification rate of product.