In　the　last　few　decades,　worldwide　scientists　have　been　motivated　by　the　promising　production　of　chemicals　from　the　widely　existing　methane　(CH4)　under　mild　conditions　for　both　chemical　synthesis　with　low　energy　consumption　and　climate　remediation.　To　achieve　this　goal,　a　whole　library　of　catalytic　chemistries　of　transforming　CH4　to　various　products　under　mild　conditions　is　required　to　be　developed.　Worldwide　scientists　have　made　significant　efforts　to　reach　this　goal.　These　significant　efforts　have　demonstrated　the　feasibility　of　oxidation　of　CH4　to　value-added　intermediate　compounds　including　but　not　limited　to　CH3OH,　HCHO,　HCOOH,　and　CH3COOH　under　mild　conditions.　The　fundamental　understanding　of　these　chemical　and　catalytic　transformations　of　CH4　under　mild　conditions　have　been　achieved　to　some　extent,　although　currently　neither　a　catalyst　nor　a　catalytic　process　can　be　used　for　chemical　production　under　mild　conditions　at　a　large　scale.　In　the　academic　community,　over　ten　different　reactions　have　been　developed　for　converting　CH4　to　different　types　of　oxygenates　under　mild　conditions　in　terms　of　a　relatively　low　activation　or　catalysis　temperature.　However,　there　is　still　a　lack　of　a　molecular-level　understanding　of　the　activation　and　catalysis　processes　performed　in　extremely　complex　reaction　environments　under　mild　conditions.　This　article　reviewed　the　fundamental　understanding　of　these　activation　and　catalysis　achieved　so　far.　Different　oxidative　activations　of　CH4　or　catalytic　transformations　toward　chemical　production　under　mild　conditions　were　reviewed　in　parallel,　by　which　the　trend　of　developing　catalysts　for　a　specific　reaction　was　identified　and　insights　into　the　design　of　these　catalysts　were　gained.　As　a　whole,　this　review　focused　on　discussing　profound　insights　gained　through　endeavors　of　scientists　in　this　field.　It　aimed　to　present　a　relatively　complete　picture　for　the　activation　and　catalytic　transformations　of　CH4　to　chemicals　under　mild　conditions.　Finally,　suggestions　of　potential　explorations　for　the　production　of　chemicals　from　CH4　under　mild　conditions　were　made.　The　facing　challenges　to　achieve　high　yield　of　ideal　products　were　highlighted　and　possible　solutions　to　tackle　them　were　briefly　proposed.