Abstract: Analyses of secondary hydrocarbon generation in sapropelic coal and its residue from pyrolitic simulation are resulted in two conclusions:(1)While secondary hydrocarbon generation begins,the phenomena of blue shift takes place,it marks the start of secondary hydrocarbon generation;(2)the location (marked with the maturity of vitrinite) and strength of the phenomena generating have affinity with original maturity,with original maturity increasing,the location gradually moves back;the difference between generating maturity and original maturity will increase at first and then decrease,the turning point is suggested in the range of 1.46%~1.80% (Ro,max).