Hulei (pinyin: hū léi) is a plucked stringed instrument with a neck-type half-pear-shaped speaker, which can be seen in the records of the Tang Dynasty. The use of Hulei was very extensive in the Tang Dynasty. Hu Lei is a musical instrument, and of course no one will play this instrument anymore. There are still two Hu Lei in the Palace Museum in Beijing.

Hu Lei is an exquisite pipa in ancient my country. Its appearance and evolution are full of legends and become a beautiful talk in the history of Chinese music.
The name of "sudden thunder" is generally interpreted as "suddenly there is thunder" when it bounces, so it gets this name, but another explanation is that it is "crocodile". Crocodiles on dry land, "sudden law" and "sudden thunder" sound close together, which should be a change in transliteration.

Hu Lei is not only an extremely delicate handicraft, but also a treasure among the existing ancient musical instruments, which is of great value to the study of Tang Dynasty music. It is the same treasure in the history of music as the pipa in the Tang Dynasty kept in the Zhenglun Institute in Nara, Japan.