He was the sole son of Namjil Wangchuk, the Duoluo Duling Junwang (多羅杜棱郡王 Duōluō Dùléng Jùnwáng) of the Sönid Right Banner and Chief of the Xilingol League.

After the fall of the Qing, Yuan Shikai promoted Demchugdongrub to the title of Jasagh Heshuo Duling Jinong (扎薩克和碩杜棱亲王 Zhāsàkè Héshuò Dùléng Qīnwáng) in 1912.

Demchugdongrub married a daughter of a Taiji (Qing aristocratic title) nobleman from his own Sönid Right Banner, and the next year had their first child, Dolgorsuren (都古爾蘇隆 Dōugǔ'ěrsūlóng).

In 1931, he succeeded to the post of the Chief of the Xilingol League after Yang Cang (楊桑 Yáng Sāng) and Sodnom Rabdan (索特那木拉布坦 Suǒtènàmù Lābùtǎn).

During September 1933, the Mongolian princes of Chahar Province and Suiyuan traveled to the temple at Bailingmiao north of Guihua and gathered in a council chamber with Demchugdongrub, who for months had been trying to found a pan-Mongolian self-rule movement.

In response, Nanjing sent Huang Shaohong as an envoy, who in the end authorized the creation of the Mongol Local Autonomy Political Affairs Committee.

The Japanese General Jirō Minami, commander of the Kwantung Army, and Colonel Seishirō Itagaki gave support to the new Inner Mongolian Autonomous Government, which they felt would weaken China and be subject to the influence of Japan.

After establishing a ceremonial Mengjiang-Manchukuo alliance in May 1935, Puyi honoured Demchugdongrub with the title of Martial Virtue Prince of the First Rank (武德親王 Wǔdé Qīnwáng).

On 24 December 1935, General Minami sent two battalions of irregular Manchurian cavalry under Li Shouxin, a squadron of Japanese planes, and a few tanks to assist the Prince in taking over the northern part of Chahar province.

The Japanese proclaimed that Demchugdongrub was on a mission to "inherit the great spirit of Genghis Khan and retake the territories that belong to Mongolia, completing the grand task of reviving the prosperity of the nationality".

Three months later Demchugdongrub, as the head of the Political Council, declared that he was the ruler of an independent Mongolia, and organized an army with the aid of Japanese equipment and training.

When Fu responded that Demchugdongrub was merely a puppet of "certain quarters" and requested that he submit to the authority of the Chiang Kai-shek's central government, Prince De's Mongolian and Manchurian armies launched another, more ambitious attack.

(Japanese soldiers fighting for Mengguguo were often executed by Chinese forces after their capture as illegal combatants, since Mengjiang was not recognized as being part of Japan).

[12] In anticipation of this attempt to take control of Suiyuan, Japanese spies destroyed a large supply depot in Datong and carried out other acts of sabotage.

In December, threatened by the Communist army, Demchugdongrub fled to the People's Republic of Mongolia and was at first welcomed there, but was later arrested by the authorities in the following February and deported to China in September 1950, where he was charged with treason.