Air leakage detection method and device for engine aftertreatment and exhaust pipeline

The invention discloses an air leakage detection method and device for engine aftertreatment and an exhaust pipeline. The method comprises: obtaining a first corresponding relation and a second corresponding relation through measurement in advance; determining that the engine is in a to-be-detected state under the conditions that the rotating speed of the engine is not smaller than a preset rotating speed lower limit threshold value, the circulating oil supply amount of the engine is not smaller than a preset circulating oil amount threshold value and the operation working condition of the engine is stable; and based on the first corresponding relation, the second corresponding relation, the target carbon loading capacity and the target exhaust flow, determining the first exhaust pressure; calculating the difference value between the first exhaust pressure and the target exhaust pressure, and obtaining a target value; and under the condition that the target value is larger than the preset threshold value, det