Abstract: Thermal simulation experiments were carried out on whole rock samples and isolated keragens from limestones of Qinglong Fm., Triasic, south Jiangsu province and of Tieling Fm., Middle Proterozoic, north Hebei province. The gaseous products, extracts were subjected to analysis using a series of techniques which include carbon isotopic analysis (MS), gas chromatography (GC), liquid chromatography (LC),infrared spectroscopy(IR),nuclear magnetic resonance (¹H-NMR), elemental analysis (EA),Rack Eval pyrolysis, thermal gravimetric analysis (TGA), X-ray refraction (XRD),electron spinning resonance (ESR) and some optical methods tvitrinite Ro, bittumen Ro and kerogen coloration). Based on the above work, the thermal evolution of carbonate source rock was characterized and some criteria were proposed for the determination of the lower boundaries of oil phase and that of the condensate-wet gas phase. These cxiteria may be used for maturity evaluation in the carbonate petroleum provinces. A comparison between the results of whole rock and isolated kercagen pyrolysis shaves that the maturation process of kerogen within the rock matrix is slightly slower than that of isolatea kerogen.