Horizontal well is one of the pivotal techniques that brought about wide-spacing and high-productivity and highly efficient development in Tarim Oilfield.This paper mainly discusses the mature and matching designing and principal of horizontal well optimizing during various periods in diverse hydrocarbon reservoirs,such as new oil and gas field exploitation,ageing oil and gas field adjustment and excavation,development of gas or condensate gas fields in Tarim Oilfield,and so on,and makes a comparison of positive .