Although dark matter (DM) contributes a large component of the mass-energy of the universe, its properties and interactions with known particles remain unknown. In light of this unsolved puzzle, searches for DM pair-produced at Large Hadron Collider (LHC) provide important information complementary to direct and indirect detection experiments in order to determine whether a signal observed experimentally indeed stems from DM. In this presentation, I will report the latest search results of DM pair production in association with a weak boson or a Higgs boson using LHC Run2 data (sqrt(s)=13 TeV) collected by the ATLAS detector. I'll demonstrate the improvement of the analysis using the state-of-the-art boosted hadronic W,Z and Higgs boson techniques. Because the observed data are found to be consistent with the expected Standard Model backgrounds, I'll show results interpreted using simplified models developed by the LHC DM forum. Finally, I will discuss the prospects of this search in the coming LHC Run2 and new ideas of the boosted Higgs tagging.