Abstract: The experiment of Doppler effect is conducted with phyphox at home by employing two smartphones which acted as the sound source and the receiver，respectively. The sound source or the receiver fell freely so that the frequency and the velocity versus times can be obtained. The gravitational acceleration and the speed of sound can be calculated through data processing. Furthermore，the measured and theoretical values are compared. The reliability of Doppler effect experiment with smartphones is verified，and the results will provide some guidance for future experiments and data processing.

Key words: smartphones, phyphox, Doppler effect, speed of sound, gravitational acceleration