As the space task is further complicated,the spacecraft energy demand is higher.Using the laser energy transmission technology to the spacecraft energy supply is more and more attention.In order to supply the gaps of current ground-based laser energy transmission,a kind of space-based laser energy transmission technology is studied on basis of the fractionated spacecraft concept.The process and models of this energy transmission are presented.Compared with the ground-based one,the advantages of space-based laser energy transmission are analyzed.According to the development situation of laser technique and aerospace technology，five key technologies that need to be achieved for realizing laser energy transmission technology are analyzed,which provides a new solution for the fractionated spacecraft energy supply.