Abstract: A microphone position calibration method for ceiling-mounted arrays is investigated in this paper. In reverberant environments, time delay estimation algorithm degrades severely, which introduces serious errors in calibrating microphone positions. Therefore, we propose a method that impulsive sound sources are used as calibration sources and the direct sound from an impulsive sound source is isolated to improve time delay estimation. The error analysis model is bulit in this paper and the simulation are performed using white noise and impulsive sound as calibration sources, respectively. The simulation results show that the proposed method can effectively suppress the influence of the reverberant field and allowed to obtain accurate positions. An experiment is carried out to calibrate the microphone positions of a spiral array mounted on the ceiling with the aperture of 3.5 m and 64 microphones in a closed room. The experimental results demonstrate the effectiveness of the proposed method