【报告摘要】A growing number of quasars found at redshifts z~6, when the universe was younger than a gigayear, requires a very efficient way of forming early supermassive black holes. The main difficulty in forming the SMBHs in galaxy centers is their long growth time, if the initial seed mass is small compared to the final product. In this talk, I will briefly introduce the direct collapse scenarios, in which gas accumulates and collapses to form an SMBH seed either with or without the intermediate stage of an super-massive star. I will show my recent work by testing this assumption by treating the optically thick part of the accretion flow using radiative transfer in the flux-limited diffusion (FLD) approximation. At last I will summary our results and show the possible observation implications.