Power flow calculation methods have been developed in decades using power injections and Newton-Raphson method. The nonlinear characteristics of the power flow to the bus voltage require Jacobian matrix reformation and refactorization in each iteration. Power network is composed by resistors, reactors, and capacitors which is a linear circuit when investigating the node voltages with the node current injections. To take the advantage of the linearity, this paper proposed to use terminal circuit model and PMU voltage phase angle measurements to simplify power flow calculation. When updating current injections at the righthand side of power flow equations and using PMU voltage phase angle measurements representing PV buses voltage phase angle, the Jacobian matrix is constant during the iteration. The simplification reduces the computational efforts and improves the computation efficiency. The proposed method is tested on the IEEE 14-bus and IEEE 118-bus standard systems. The results are validated by traditional power flow solution and the computation efficiency is demonstrated.