Abstract: Oil shale is an important unconventional oil and gas resources in China. Its development and utilization is of great significance to alleviate the problem of energy shortage in China. Due to the high ash content of oil shale,the mass transfer resistanceof gaseous matter against the intraparticle is quite high,which has significant effects on the distribution of pyrolysis products of oil shale. In this paper,a pyrolysis experimental system for single particle oil shale was built to study the influence of mass transfer resistance of ash layer on pyrolysis characteristics of single particle oil shale,which can provide a more essential understanding of the pyrolysis process of oil shale and provide a basis for the construction of pyrolysis model. The effects of particle size,pyrolysis temperature and other factors on the distribution of pyrolysis products were studied,and the distribution of pyrolysis products of single grain oil shale with different gas flow rates,particle sizes and pyrolysis temperatures was obtained. It is found that gas flow rate has little effect on the distribution of pyrolysis products of oil shale particles. With the particle size increasing,more secondary pyrolysis reactions happens before the primary pyrolysis products are separated out. Part of the pyrolysis products are fixed in the semi coke again through the complex secondary pyrolysis reaction,which leads to the decrease of shale oil proportion and the increase of gas proportion in the products.The larger the particle size is,the more obvious the secondary pyrolysis reaction is at higher temperatures. As a result,the proportion of shale oil in the pyrolysis products of coarse particles increases first and then decreases with the increase of pyrolysis temperature,while the proportion of shale oil in the pyrolysis products of fine particles increases with the increase of pyrolysis temperature.