关键词: 蔬菜价格, 周期波动, HP 滤波法, BP 滤波法

Abstract: During recent years, vegetable prices have been fluctuating frequently in China; and difficult selling and expensive buying has occurred from time to time．By virtue of HP and BP filter methods, this paper quantifies vegetable and its main varieties to find out long-term change factors, seasonal factors, circulating
factors and random factors affecting vegetable prices, and then analyzes the law of price fluctuation．The results of analysis indicate that vegetable prices show the linear trend of overall long-term growth, with significant seasonal fluctuation but no evident random fluctuation．Storage tolerant varieties in centralized producing areas have evident price fluctuation cycle with relatively distinct seasonal changes; while those in scattered producing
areas have no obvious price fluctuation cycle but with evident seasonal changes．Weather factors exert great influences on price fluctuation of greenhouse vegetables and leafy vegetables, with characteristics of significant seasonal fluctuation but no obvious cyclical fluctuation characteristics．

Key words: Vegetable price, Cyclical fluctuation, HP filter method, BP filter method