Nha Nature Reserve lies in Moc Chau district in the south-west of Son La province. To the south and east the nature reserve is bordered by Hoa Binh and Thanh Hoa provinces, while, to the west, it is bordered by Laos. The highest point in the nature reserve, Mount Pha Luong at 1,970 m, lies on the mountain ridge that forms the international border with Laos