Asymmetric faults in the power grid will lead to voltage drop at the point of common coupling (PCC), even resulting in severe risk e.g. cutting machine. However, the traditional voltage support strategy is easily affected by the output of the unit, and cannot flexibly support the PCC voltage. For the above problems, an optimal voltage support strategy considering the photovoltaic and storage output under asymmetric faults is proposed. First, the principle of voltage support under asymmetric fault is analyzed, and the voltage support equation is deduced. Then, based on the above equation, taking the grid-connected standard's operating requirements for PCC voltage as the target, and considering the current peak value and active power fluctuation amplitude as constraints, the ideal voltage support scheme is obtained. Further, according to the actual output of photovoltaic and energy storage and the ideal reference value of active power, the output scenarios of photovoltaic and energy storage are classified. When the ideal current reference value cannot satisfy the optimal solution, the voltage support equation and the corresponding constraint equation are combined to establish a nonlinear equation system about each component of the current, and the optimal current reference value can be solved. Finally, the effectiveness and flexibility of the proposed strategy are verified by simulation.