Rational determination and reduction of local energy loss of oil flow at pipe junctions are of important significance to improve hydraulic pipeline's work efficiency, especially for complex hydraulic pipeline connected by isodiametric T-type ducts with sharp comers to get combined and divided flow. From this point of view, the formulae of resistance loss for combined flow and divided flow through isodiametric T-type duct with sharp comers as well as the correlations of resistance loss coefficients in the branches of the duct are derived using energy method. On this basis, resistance characteristics of hydraulic oil in the duct are obtained by numerical simulation of different flow modes, which are commonly applied in hydraulic pipelines, using computational fluid dynamics (CFD) method, and the reasons for the resistance loss are analyzed based on the pressure change mechanism in the flow field. A part of simulation results was validated with the reference data. The research shows that for combined flows the resistance loss of symmetrical is lower than that of tmsymmetrical to obtain low speed in common branch, but to gain high speed is quite the contrary, for divided flows, the symmetrical is always a reasonable choice to reduce resistance loss. These conclusions can be applied to optimize the design of hydraulic pipeline.