Abstract: It is difficult to to develop economically thin-scattered-weak energy oil reservoirs with directional well because these kinds of oil reservoirs are thin in oil reservoir layers, small in sand bodies, scattered in distribution and weak in natural energy. The horizontal well can improve the single well production during the early period, but due to insufficient in formation energy, production declines significantly, and the problem of low oil recovery can not be solved fundamentally. Waterflood development can solve the problem of weak formation energy, but the development cost will increase, it is difficult to obtain good economic benefits by waterflood development due to the small scale of reserves. With H4 oil reservoir of X oil field as an example, multi-bottom and multi-branch horizontal wells and formation water back dumping technology have been discussed in this paper. On the basis of fine reservoir description, the thin-scattered-weak energy oil field has been develop effectively and economically with multi-bottom and multi-branch horizontal wells and formation water back dumping technology, and good development effect has been achieved. This technology can also be used in developing economicly and effectively the other similar oil fields with difficult procucing reserves.