Zeolitic　imidazolate　frameworks　(ZIF)-derived　catalysts　are　being　extensively　investigated　for　the　oxygen　reduction　reaction　(ORR)　due　to　its　low　cost,　high　tunability,　and　facile　fabrication.　However,　an　understanding　of　the　critical　role　of　temperature　during　pyrolysis　remains　lacking,　which　makes　the　design　of　catalysts　by　thermal　activation　rely　on　empirical　engineering.　In　this　work,　we　use　ZIF-67　as　a　model　material　to　study　the　impact　of　temperature　on　microstructural　evolution　by　in　situ　transmission　electron　microscopy.　Microstructural　features　of　cobalt　precipitation,　nitrogen　loss,　and　porous　carbon　support　formation　were　investigated　and　semi-quantified.　A　tradeoff　between　the　microstructural　features　is　revealed　and　confirmed　by　the　ORR　performance.　By　understanding　the　temperature-microstructure-ORR　performance　relationship,　we　further　design　a　simple　low-temperature　pyrolysis　strategy　and　achieve　outstanding　ORR　activity.　Although　demonstrated　on　ZIF-67,　the　critical　role　of　temperature　as　disclosed　by　this　work　is　beneficial　for　all　ZIF-related　materials　to　further　boost　ORR　performance.　Meanwhile,　our　one-step　strategy　is　easy　to　implement　and　allows　for　scaling　up　for　industrial　application.