[Objective] Change characteristics of the primary ecosystem services in Horqin sandy land under the implementation of ecological construction projects were studied in order to provide a scientific basis for future ecological protection and construction in this area.[Methods] The temporal-spatial changes of carbon sequestration, water source conservation, and soil conservation in this region from 2001 to 2018 were evaluated by using existing ecosystem service assessment methods.[Results] ① The land use types in Horqin sandy land were mainly farmland, forestland, and grassland. During the implementation of the ecological construction project, the area of forestland and farmland increased by 8 448 km² and 3 280 km² respectively, but the area of grassland decreased by 12 639 km². ② Carbon sequestration in this region increased steadily. Carbon sequestration of forestland and farmland increased, while that of grassland decreased. However, carbon sequestration of grassland was still the highest. ③ The amount of water conservation of this region first increased and then decreased slightly, but the amount of water conservation in forestland continued to increase. ④ The amount of soil conservation in Horqin sandy land increased continuously, with an increase of about 1.38×10⁷ t, with forestland showing the largest increase. The spatial distribution of soil conservation was obviously limited by the terrain, with the total amount of soil conservation being highest in the west and lowest in the east.[Conclusion] The ecological construction projects in Horqin sandy land have produced good effects and significant ecological benefits.