Dayi (under the jurisdiction of Chengdu, Sichuan Province) generally means Dayi County
Daylai County is located in the transition zone of Chengdu Plain to northwest Sichuan Plateau. Daylai County borders on Qionglai Mountains. It is adjacent to Chongzhou City in the east, Xinjin District in the southeast, Qionglai City in the southwest, Lushan County and Baoxing County in Ya 'an City in the west, and Wenchuan County in Aba Prefecture in the north. The total area of the county is 1327 square kilometers. According to the seventh Census, as of 0:00 on November 1, 2020, the permanent population of Dayi County was 515,962.

The topography of Dayi County, which is high in the northwest and low in the southeast, is gradually reduced in a ladderlike way. Three major topographic areas, namely mountain, hill and plain, appear successively and have a geomorphic structure of "seven hills, one water and two fields". Mountain, hill and plain account for 60.5%, 16.7% and 22.8% of the total area of the county respectively. Qionglai Mountain extends into the country from northwest to southeast, and runs through the west and north hill areas of the county. The highest point in the northwest is the Miao Ji Ling in Xiling Town, 5364 meters above sea level, the first peak in Chengdu.

Dayi County has three streets and eight towns. It is a subtropical monsoon humid climate. Dayi County has a long history and prosperous culture. Beautiful scenery, rich tourism resources. The top 100 counties and cities in Western China. In March 2021, it was named as an advanced district (city) county of Chengdu in 2020 to implement the Rural revitalization strategy and promote the integrated development of urban and rural areas.
In 2019, Dayi County achieved a gross regional product (GDP) of 28.569 billion yuan.