Hanging the imperial banner is an ancient ritual of offering sacrifices to heaven and earth and praying for a good harvest in the ancient Shu witchcraft. Zhang Ling founded Taoism based on the ancient Shu witchcraft and incorporated the hanging of the imperial banner into the main content of Taoist fasting and offering rituals. It is also the source of today's Chinese knot.

According to the "Collection of the Original Practices of the Jade Emperor - The Ritual Chapter", "Anyone who writes the holy name of the Jade Emperor on a long banner and hangs it high in the sky will be able to form a spiritual seal and receive infinite blessings..." The so-called "banner-making" refers to using a yellow cloth more than one meter long, with the holy name of the Jade Emperor written on it, and red cloth as the foot of the banner. The red cloth is divided into five ribbons, and five copper coins are strung at the end of each strand, symbolizing the five thunders. This is called "Huang Yan". During the practice, the banner is hung on a large bamboo pole three meters above the ground, and through high-level practice, the five ribbons at the foot of the banner will form a "cloud seal" by themselves. The "cloud seals" formed will change every day with the progress of the fasting and offering rituals until the day when the merits of the ceremony are complete, when the "Thanking the Banners and Returning the Gods" ceremony is held, and finally the meaning of the "cloud seals" formed this time is interpreted according to the "Imperial Banner Cloud Seals".