Metal-organic　frameworks　(MOF)　have　recently　emerged　as　versatile　precursors　to　fabricate　functional　MOF　derivatives　for　oxygen　evolution　reactions　(OER).　Herein,　we　developed　a　controlled　partial　pyrolysis　strategy　to　construct　robust　NiCo/Fe3O4　heteroparticles　within　MOF-74　for　efficient　OER　using　trimetallic　NiCoFe-MOF-74　as　precursor.　The　partial　pyrolysis　method　preserves　the　framework　structure　of　MOF　for　effective　substrates　diffusion　while　producing　highly　active　nanoparticles.　The　as-prepared　NiCo/Fe3O4/MOF-74　delivered　remarkably　stable　OER　current　with　an　overpotential　as　low　as　238　mV　at　10.0　mA　cm(-2)　and　an　Tafel　slop　of　29　mV/dec,　outperforming　those　of　pristine　NiCoFe-MOF-74,　totally　decomposed　MOF　derivatives,　and　most　reported　non-noble　metal　based　electrocatalysts.　The　key　for　the　formation　of　NiCo/Fe3O4/MOF-74　nanostructures　is　that　the　metals　can　be　decomposed　from　NiCoFe-MOF-74　in　the　order　of　Ni,　Co,　and　Fe　under　controlled　heat　treatment.　Density　functional　theory　calculations　reveals　that　the　underlying　NiCo　promotes　the　OER　activity　of　Fe3O4　through　exchange　stabilization　of　active　oxygen　species.