The timber-built Grand Theater House is to be found in the eastern part of the garden, with a collection of old-time pavilions standing beside it. The courtyard is rectangular, with peonies planted in the four corners, so it was known as “Peony Yard.”

The Theater was also called Yishen House, which means “relaxed and happy place”, after a plaque written by Emperor Kangxi that hangs in the building.

It has survived more than 100 years of northern China's changeable weather and still stands firm. The spacious stage offers Beijing Opera, Kunqu Opera and selections of royal music performed in traditional stage settings each day.

There are two ways to get the Grand Theater House: one via the lane along the east wall was for performing troupes and the audience who were invited by the royal family, and the second via the other part of the garden for the VIPs and the most intimate friends of the royal family.

Many stones were piled into the form of a mountain between the theater house and the garden so that the audience and the performing troupes couldn’t see the garden, and the noisy crowd in the opera hall wouldn’t bother any royal family members relaxing in the garden.

The Grand Theater House occupies an area of 685 m² and the stage covers 52 m². The room in the south is a powder room for the performers. The north balcony is for the prince and his VIP guests.

This is the most luxurious private theater house in ancient China. Even in the Emperors’ Forbidden City, Beihai Park and the Summer Palace, there is nothing to compare with it.