The UN-REDD Mongolia National Programme has studied about forest carbon emissions, and enhance and sustainably manage its carbon stocks, through the implementation of REDD+ activities since 2011. However, the current assessments seem to remain uncertain, the study for estimating carbon storage based on field survey are still rare. Because the <i>Haloxylon ammodendron</i>, where Gobi desert ecosystems are covering large areas, it is necessary to develop a modelling approach applying remote sensing. The study area is locating in Gobi-Altai province, Trans-Altai area as the south-western part of Mongolia. A total of 32 plots were established on eighth different land cover types to represent the range of variability. The study was used high spatial resolution imagery of Pleiades-1 and both of active and passive data from Sentinel-1 and Sentinel-2. The growing height in 32 plots is ranging from 20 to 460 cm with between 0.002 and 544.9 cm<sup>2</sup> for basal area and between 526.5 and 166106.0 cm<sup>2</sup> for canopy area, respectively. Shrub density is very high in plot 4 (n=135) and plot 5 (n=117) with low above-ground biomass 12 kg and 10.9 kg. The backscatter (dB) values of vegetated area and non-vegetated were comparable, −27.86 and −17.36 in VH polarisation and −22.72 and −10.61 in VV polarisation, respectively. Model-M1 was best demonstrated when a combination of vegetation coverage area was used as Pleiades-1 and Sentinel-2 derived vegetation cover data. For model-M9, the results were comparable to model-M1 but with lower the coefficient of determination. In this work, NDVI and MSAVI appear as a good indicator of biomass mainly because it does not saturate in sparse shrubs and is more sensitive to canopy parameters.