The Hoang Lien Sa Pa National Park was created in 2002, covering 29,845 hectares in Viet Nam's mountainous province of Lao Cai. The Hoang Lien Son range of mountains dominates the district, which is at the eastern extremity of the Himalayas. The Park borders Phong Tho District in Lai Chau Province to the east, the communes of Ho Mit, Pac Ta, Nam Can in Than Uyen District to the south and the Ta Giang Phin, Ta Phin, Ban Khoang, Trung Chai communes in Sa Pa District to the north. The Park has been demarcated into 11,800 hectares of strictly protected area; 17,900 hectares of ecology recovery area; and 38,724 hectares as buffer zone.
The Park contains Viet Nam's highest mountain, Phan Xi Pang or Fansipan, which has an elevation of 3,142 meters above sea level. The lowest point is 380 meters but most of the nature reserve lies above 1,000 meters. The flanks of the mountains are very steep and many areas are inaccessible. Between Fansipan Mountain and Sa Pa town, lies the Muong Hoa valley, which has been terraced for wet rice agriculture. This valley becomes wider towards the east of the nature reserve. The climate in the area is moderate and rainy in summer (May-August), and foggy and cold with occasional snowfalls in winter.