提出了旅游本底趋势线的概念，依据１９７８年～１９９５年共计１８年客流量统计数据，建立了西安市境外客流总量、外国人和港澳台胞３条本底趋势线；利用本底线自然延伸的“预测”功能，预测未来４年西安市境外客流量变化，外国人将呈增长趋势，港澳台胞和华侨将呈下降趋势，总体客流量仍呈增长趋势。 Based on the 18-year statistics of passenger flow from 1978 to 1995, this paper establishes the total amount of passenger flows outside Xi’an and the three background-oriented trend lines of foreigners and compatriots in Hong Kong and Maucao. By using the bottom line, Extending the “prediction” function, predicting the changes in the overseas passenger traffic in Xi’an in the next four years and increasing foreigners’ growth. The numbers of compatriots in Taiwan, Hong Kong, Maucao and overseas Chinese will show a downward trend, and the overall passenger flow will continue to show an upward trend.