The ‘100 Hz’ pure tone（hum） from the power transmission line is remarkable in rainy day

and has an increasing risk in high-altitude areas. In order to prevent the residential area from the crest area of the standing wave

we studied the standing wave distribution of ‘100 Hz’ pure tone. According to the ‘generation’ of hum under the condition of the heavy rain proposed by American EPRI

considering the ground reflection of sound waves and interference between the sound waves

we established a computational model of standing waves of the pure tone and obtained a distribution rule. Statistical analysis of ‘100 Hz’ pure tone test data is made under heavy rain conditions

and compared with the calculation results. The calculation results show that

unlike A-weighted sound level

the distribution of ‘100 Hz’ pure tone of double circuit lines on the same tower with inverse phase sequence is asymmetric and vibration attenuated. The attenuation speed is slower than that of A-weighted sound level; Near transmission lines

the distance between the adjacent peaks is smaller; far from transmission lines

the distance between the adjacent peaks is increased. The value of amplitude decreases monotonically several hundred meters away from transmission lines.