Eight types of samples:crude oil,chloroform bitumen A,oil fractions(saturated hydrocarbon,aromatic hydrocarbon,resin and asphaltene) ,source rock and kerogen,have been pyrolyzed in laboratory. The products have also been systematically analyzed. The results indicate that gaseous hydrocarbons yields for different types of samples at various temperatures are different,especially for different fractions of crude oil. There is difference for molecular compositions. The C2/C3 ratios of cracking gases in different types of samples have positive relationships with C2/iC4 as well as pyrolysis temperatures. Moreover,the ratios of C2/C3 and C2/iC4 are about 2 and 10,respectively,at the temperature of 500℃― 550℃. However,when the temperature is higher than 500℃,the ratios of C1/C2,C1/C3 and dryness index for gases cracking from source rock and kerogen are higher than those from oil and bitumen,indicating an important different feature between oil-cracked gases and kerogen-cracked gases at the high or over-mature stage. The ratios of C1/C2,C1/C3 vary more than 10% at 500℃―800℃. In this paper,experimental results can provide important academic foundation and useful geochemical parameters for distinguishing of oil-cracked gases and kerogen-cracked gases. Eight types of samples: crude oil, chloroform bitumen A, oil fractions (saturated hydrocarbon, aromatic hydrocarbon, resin and asphaltene), source rock and kerogen, have been pyrolyzed in laboratory. The results have that been been systematically analyzed. There are differences for molecular compositions. The C2 / C3 ratios of cracking gases in different types of samples have positive relationships with C2 / iC4 as well as the ratio of C2 / C3 and C2 / iC4 are about 2 and 10, respectively, at the temperature of 500 ° C. to 550 ° C. However, when the temperature is higher than 500 ° C., the ratios of C1 / C2, C1 / C3 and dryness index for gases cracking from source rock and kerogen are higher than those from oil and bitumen, indicating an important different feature between oil-cracked gases and kerogen-cracked gases at The this ratio of C1 / C2, C1 / C3 varies more than 10% at 500 ° C.-800 ° C. In this paper, experimental results can provide important academic foundation and useful geochemical parameters for distinguishing of oil- cracked gases and kerogen-cracked gases.