Cross　laminated　timber　(CLT)　is　becoming　increasingly　popular　for　constructing　multiple-story　buildings　due　to　its　alignment　with　Sustainable　Development　Goals　of　United　Nations.　However,　such　structures　can　be　susceptible　to　excessive　vibrations　during　earthquakes.　While　tuned　mass　dampers　(TMDs)　can　be　used　to　control　these　vibrations　in　CLT　structures,　their　effectiveness　can　be　reduced　due　to　the　lightweight　nature　of　CLT　and　changes　in　its　structural　mass　or　deterioration　of　the　wood.　To　address　this　issue,　this　paper　proposes　the　use　of　shape　memory　alloy-based　semi-active　tuned　mass　dampers　(SMA-STMDs)　for　controlling　vibrations　in　CLT　structures.　This　study　includes　the　design　and　experimental　testing　of　a　full-scale,　novel　spring-pendulum　combined　SMA-STMD　system,　which　utilises　the　mechanical　properties　of　SMAs　that　change　with　temperature　to　achieve　semi-active　control.　Finite　element　method　simulations　demonstrate　that　the　proposed　SMA-STMD　system　can　effectively　reduce　structural　seismic　vibrations　in　CLT　structure.　By　adjusting　the　SMA　temperature,　the　SMA-STMD　system　can　effectively　address　the　issue　of　TMD　system　off-tuning　caused　by　changes　in　the　CLT　structural　properties.　Overall,　the　proposed　SMA-STMD　system　offers　a　promising　solution　for　seismic　control　in　CLT　structures　and　has　the　potential　to　promote　the　development　of　CLT　structures.