In this paper,we adopt standard Si-based p rocess to develop a phototransistor which is compatible with the standard process,and solve the compat ibility problems between the structure of phototransistor and standard processes.Furthermore,we achieve th e optimal design of its structure and properties.According to standard Si-based process from CSMC,based on the theoretical analysis,we adopt Silvaco to build and sim ulate the phototransistor by changing the structure of it.After packaging and te sting,the phototransistors with the base areas of 40μm×40μm,50μm×100μm,80μm×100μm and 100μm×100μm are achieved.The experimental result s show that the performance of the designed photosensitive transistor is good.The responsivity can reach 2.02A/W, magnification factor can be up to 60,and the maximum bandwidth can reach as hi gh as 50MHz.Furthermore,the low cost and compatibility of standard Si process make it suitable for fast optical coupler,optical data rec eivers and other optical devices.