The Ground-source Airborne Time-domain Electromagnetic (GATEM) system has advantages for high efficiency and complex areas such as mountainous zone. The widely used section interpretation method, ignoring the impact of flight height, which seriously affects the interpretation and imaging accuracy of shallow anomalies. The PID controller iteration downward continuation method is proposed. Based on the original continuation iteration method, the differential coefficient and integral coefficient are added. The result shows that the new method remarkably decreases the iteration number and the accuracy are verified by comparison with the numerical integration solution. The PID controller iteration downward continuation method is applied to the interpretation of GATEM data. For synthetic data, the after continuation interpretation results are closer to the true model than the z = 30 m interpretation results. The method is also applied to GATEM field data in Yangquan City, Shanxi Province, China. The interpretation performs using PID controller iteration downward continuation results in a reliable GATEM field.