In this paper, the molecular structures of five kinds of original natural rubber (NR) samples produced by different coagulation methods and from different regions(within six months) were studied using a pyrolysis (at 550°C) gas chromatography/mass spectrometry (py-GC/MS) technique. The result showed that the similar molecular structures of the major degradation products, monomers (2-methyl-1,3-butadiene and 1,3-pentadiene) along with dimers of a large number of 1-methyl-4-(1-methylethenyl)cyclohexenes (limonenes) and small amounts of tran limonenes, were all found in three original NR samples, SMR20 and STR20 made all by natural coagulation, and MC-SCR5 coagulated rapidly by microorganisms. Also, the relative productivity (57.48%-59.27%) of the monomers are similar. But the some differences of the molecular structures, the monomers which included 1,4-pentadiene, 3-methyl-1,2-butadiene and 2-pentyne along with more tran limonenes dimers were exhibited in two original NR samples, GSR-RSS3 coagulated by new technology and HN-SCR5 by acetic acid, their relative productivities (61.22% and 65%) have also more differences, as compared with that of the bio-coagulated natural rubbers. Conbine our previous and current works, a conclusion can be obtained that the rubber-productions of origin is not the main factor affecting the molecular structures of natural rubber, but the coagulation processing.