Abstract: With △C theory,it is believed that a pyrolysis will take place only in the altered carbonate of hydrocarbon generation under the temperature range of 500~600℃.However,through the experiments,the author concludes that much pyrolyses will occur in the secondary carbonates of other origins at the temperatures of 500~600℃.It means that these secondary noncrystalline carbonates( including △C)are the major pyrolytic products within the temperature range.In view of this,the author modifies their measurements based on the functional relationships between the carbonates.