Based on the model of ecological footprint, combined with the ecological consumption and its structure character of tourists, this paper applied the tourism ecological footprint model into the assessment of the sustainable development of regional tourism. Then the paper analyzed the concept of ecological footprint and founded the calculating submodels of tourism ecological footprint including the model of transportation, shopping, food and beverage, accommodation and sightseeing. Taking Xi′an city as an example, we calculated and analyzed its tourism ecological footprint in 2004. The result reveals that the tourism ecological footprint of Xi′an city is 0.1194hm² per capita in 2004, the tourism ecological carrying capacity per capita is 0.0198hm², and the tourism ecological deficit per capita achieves 0.0996hm²，which proves that the tourism of Xi′an city is in “the state of unsustainable development”. To ensure sustainable development of tourism, effective measures must be taken to rationalize the use of ecological resources.