The invention provides a detecting device for a fixing hole of an automobile front grid and belongs to the field of detecting equipment. The detecting device comprises a base, a controller, a plurality of fixing mechanisms and detecting mechanisms. The fixing mechanisms are arranged on the edge of the upper side face of the base, the detecting mechanisms are connected with the base through cables, and the controller is connected with the detecting mechanisms. One ends of the fixing mechanisms are fixed to the base through connecting parts, and the other ends of the fixing mechanisms are provided with screw holes and bolts. One ends of the detecting mechanisms are fixed to the base, and the other ends of the detecting mechanisms are provided with detection heads comprising elastic sleeves and detection cores. A piezoelectric sensor is arranged between each elastic sleeve and the corresponding detection core. The radius of each detection core is smaller than the radius of the fixing hole, and the radius of the outer surface of each elastic sleeve is larger than the radius of the fixing hole. The controller comprises a control module, a collection module, a processing module, a storage module, an alarm module and a display module. According to the detecting device for the fixing hole of the automobile front grid, the size of the hole diameter can be obtained through deformation of the elastic sleeves and stress of the piezoelectric sensors, the structure is simple and the device can be used conveniently.