The 77th Group Army (Chinese: 第七十七集团军; pinyin: Dì Qīshíqī Jítuánjūn), Unit 31667, formerly the 13th Group Army, is a military formation of the Chinese People's Liberation Army Ground Force (PLAGF).

The 77th Group Army is one of thirteen total group armies of the PLAGF, the largest echelon of ground forces in the People's Republic of China, and one of two assigned to the nation's Western Theater Command.

[3] During the Sino-Vietnamese War, the Kunming Military Region took responsibility for Chinese operations during the Battle of Lào Cai, which involved the 11th and 13th Armies from the Kunming Military Region itself, and the 14th Army from the Chengdu Military Region, totaling about 125,000 troops.

[5] The invasion comprised three prongs of advances: while the 11th Army was assigned to attack Phong Thổ before hooking up to Sa Pa and Lào Cai from the west, the 14th Army was ordered to take Mường Khương and move against Lào Cai from the east; the central thrust was undertaken by the 13th Army, targeting Lào Cai itself, as well as the township of Cam Đường to the south.

[6] Blasko 2002, drawing upon the Directory of PRC Military Personalities, 1999 and 2000 editions, wrote that the 13 GA (MUCD 56005), at Chongqing, comprised the 37th Motorized Infantry Division (MUCD 56013), the 149th Motorized Infantry Division (MUCD 56016) at Emei, Sichuan, an Armored Brigade (MUCD 56017) at Pengzhou, Sichuan, an Artillery Brigade (MUCD 56014) at Chongqing, and an Anti-Aircraft Artillery Brigade (MUCD 56018) at Mianyang, Sichuan.