Six　natural　clays　with　a　predominant　clay　mineral　of　illite　and　two　pure　clay　minerals　(kaolinite　and　smectite)　were　mixed　with　organic　matter　to　prepare　64　samples　of　organic　clays　containing　different　organic　compounds　at　different　contents.　The　organic　compounds　are　classified　into　two　categories　(insoluble　and　soluble　in　water)　for　studying　their　effects　on　physical　properties　of　organic　clays　investigated.　When　original　clays　are　mixed　with　organic　material　insoluble　in　water,　the　particle　size　distributions　and　the　particle　densities　of　organic　clays　can　be　approximately　determined　pro　ratio　of　each　component.　Adding　humic　acid　into　original　clays　causes　little　aggregate　or　disperse　action　on　solid　particles.　The　Atterberg　limits　of　organic　clays　containing　organic　matter　insoluble　in　water　vary　with　organic　content　in　a　nonlinear　fashion,　and　its　changing　rate　depends　on　the　liquid　limits　of　original　clays.　On　the　other　hand,　when　original　clays　are　mixed　with　organic　compounds　soluble　in　water,　dissolved　organic　matter　in　pore　water　should　be　taken　into　account　for　measuring　their　Atterberg＇s　limits.　Atterberg＇s　limits　of　organic　clays　containing　organic　matter　soluble　in　water　are　greatly　affected　by　the　predominant　clay　mineral　of　original　clays.　For　the　original　clays　with　a　predominant　clay　mineral　of　illite　and　kaolinite,　liquid　limit　increases　with　the　increase　in　organic　content,　but　contrary　changing　fashion　is　found　for　smectite.　©　2016　Elsevier　B.V.