A system and method for air calibration in a Computed Tomography (CT) imaging system are provided. A first set of data associated with air in a scanning area may be obtained. A second set of data associated with an object in the scanning area may be obtained. The second set of data based on the first set of data may be calibrated, and a set of reference values generated by a neural network model may be used to perform the calibration. A third set of data based on the calibration of the second set of data may be generated. Based on the third set of data, a CT image of the object may be generated.