The fatty acid compositions of Jatropha oil and Vernicia oil are strikingly different, which leads to a great difference in combustion performance, low temperature performance and oxidation stability. A comparative transcriptomic study was made in Vernicia and Jatropha, with a focus on the gene regulation of differential oil accumulation process. Transcriptome sequencing was conducted with seeds at the initial-and fast-stage of oil accumulation from both. More than 24 billion bases of cDNA sequence were obtained, with 49,583 and 45,414 high-quality unigenes identified for Vernicia and Jatropha seeds, respectively. Multiple comparative transcriptome approaches revealed a number of species-specific fatty acid desaturases (FAD2, FADX, FAH12 etc.) contributing to their differentiated fatty acid compositions in seeds of Vernicia and Jatropha. Meanwhile, the results suggested that DGAT majorly regulates TAG synthesis than PDAT in Vernicia seed, and PDAT may have more important role regulating TAG synthesis in Jatropha seed than in Vernicia seed. It was also implied that specific oleosins involving in oil bodies may have member bias and may affect lipid contents in seeds of Vernicia and Jatropha, as some of which were 30-50 fold up-regulated (with their RPKM values over 10,000 at fast-stage). Some important factors were identified and can differentially regulate lipid pathways in seeds of Vernicia and Jatropha.