With higher energy efficiency and less carbon intensive, widespread application of electric vehicle (EV) becomes a big trend in many transportation systems. Many cities start their green energy revolution of electric bus and taxi in public transportation systems. In this paper, value chain analysis and life cycle cost (LCC) are utilized to compare the operation feasibility of battery-charging-mode and battery-swapping-mode electric taxi. Quantitative cash flow analysis is presented to evaluate the profitability of the two different modes. The emission reduction of slow charging in battery-swapping-mode is also calculated. By analysis and calculation, it is found out that the Battery-Swapping-Mode needs larger investment to purchase reserve batteries at the initial state, but it will boost the service capability greatly, which is mainly resulted from releasing pure electric taxis' potential operating time and improving the profitability. Besides, the improvement of service ability benefits the charging service providers' profitability, drivers' waiting time and the taxi leasing companies could fully enjoy the market expanding of business growth without the existing bottleneck of the Battery-Charging-Mode. Meanwhile, we find that the slow charge of Battery-Swapping-Mode causes less impact and less harmonic pollution to the power grid, extends the battery operation life, improves charging efficiency and reduces pollutant emission, which conducive the widespread application of electric vehicle in long-term development.