From September 2006 to December 2007, we surveyed population densities of khulan (Equus hemionus) and goitred gazelle (Gazella subgutturosa sairensis) in the Mt. Kalamaili Ungulate Nature Reserve using the distance sampling method. Total length of the transect lines for investigating khulan was 6,696.4 km, altogether, we recorded 7,758 khulan. Total length of the transect lines for investigating goitred gazelle was 8,428.84 km, and we recorded 8,586 goitred gazelles. We estimated the density and encounter rates of khulan and goitred gazelle with the interactive computer program Distance 5.0. From spring to autumn, the encounter rate (the number of observed individuals/km) of khulan varied between 0.058-0.092 individuals/km, whereas that of goitred gazelle varied between 0.096-0.342 individuals/km. Suitable habitat for khulan in Kalamaili Ungulate Nature Reserve was 5,800 km2, we estimated population densities of khulan as 0.55 ± 0.20 individuals/km 2 in spring, 0.60 ± 0.13 individuals/km 2 in summer, 0.78 ± 0.19 individuals/ km 2 in autumn, and 0.54 ± 0.14 individuals/ km 2 in winter in the survey area, respectively. There were 3,379 khulan in spring, 3,965 khulan in summer, 5,318 khulan in autumn, and 3,829 khulan in winter, respectively. Suitable habitat for goitred gazelle were 10,000 km2in spring and winter, 12,000 km2 in summer, and 15,000 km2in autumn. We estimated the population densities of goitred gazelle as 1.14 ± 0.18 individuals/km 2 in spring, 0.95 ± 0.12 individuals/km 2 in summer, 1.08 ± 0.18 individuals/km 2 in autumn, and 1.54 ± 0.31 individuals/km 2 in winter, respectively. We calculated the numbers of goitred gazelle as 14,286 in spring, 6,628 in summer, 8,337 in autumn, and 19,677 in winter. We gave recommendation of using the survey transects and survey data as baseline data for long-term monitoring on klulan and goitred gazelle in the Mt. Kalamaili Ungulate Nature Reserve.