Small photovoltaic (PV) power station generally connects the grid at 380 V, medium PV power station connects the grid at 10~35 kV. Because the arrangement range of PV modules is small and the grid voltage is low, there is no collecting power line in the small PV power station, and in the medium PV power station, the voltage of collecting power line is equal to the grid voltage and the selection is relatively simple. However, for large-scale substation PV power station, the grid voltage is more than 66 kV, the arrangement range of PV modules is large, the manufacturing cost of collecting power line is also high, and it is difficult to make a choice between 10 kV and 35 kV. This paper built the model for a 200 MW PV power station, as well as compared the manufacturing cost of collecting power line at two kinds of voltage from the aspects of investment and loss. The research results could be a reference for the design of PV power plant and relevant research departments.