Six　coal　samples　of　different　ranks　have　been　used　to　prepare　single-layer　graphene　quantum　dots　(S-GQDs).　After　chemical　oxidation　and　a　series　of　centrifugation　separation,　every　coal　could　be　treated　into　two　fractions,　namely,　Coal(A)　and　Coal(B).　According　to　the　characterization　results　of　TEM,　AFM,　XRD,　Raman　and　FTIR,　Coal(A)　was　revealed　to　be　mainly　composed　of　S-GQDs,　which　have　an　average　height　of　about　0.5　nm　and　an　average　plane　dimension　of　about　10　nm.　The　obtained　S-GQDs　showed　excitation-dependent　fluorescence　and　excellent　electrochemiluminescence.　Coal(B)　was　found　to　be　some　other　carbon-based　nanomaterials　(CNMs),　including　agglomerated　GQDs,　graphene　oxide,　carbon　quantum　dots　and　agglomerated　carbon　nanocrystals.　Generally,　low-ranked　coals　might　be　more　suitable　for　the　preparation　of　S-GQDs.　The　production　yield　of　S-GQDs　from　the　six　investigated　coals　decreased　from　56.30%　to　14.66%　when　the　coal　rank　increased　gradually.　In　contrast,　high-ranked　coals　had　high　production　yield　of　Coal(B)　and　might　be　more　suitable　for　preparing　other　CNMs　that　were　contained　in　Coal(B),　although　those　CNMs　were　difficult　to　separate　from　each　other　in　our　experiment.