Abstract:Based on data of vegetable prices from 2002 to 2012,this paper uses time series decomposition and H-P filtering technology to decompose vegetable prices into seasonal fluctuation,random fluctuation,cyclical fluctuation and long-term trend and it also measures the contribution rate of fluctuation elements to vegetable price fluctuations.The result shows that seasonal factor is the most important factor that result in the change of vegetable prices,with the average contribution rate of 62.3%.The years between 2002 and 2012 can be divided into six cycles,both time span and fluctuations of cycle are big trends; the contribution rate of cyclical fluctuations to vegetable prices change is 23.6%.And abnormal emergency is the principal cause of vegetable prices caused by random fluctuations; the contribution rate of random fluctuation is 14.1%.Long-term trend of vegetable price,from sustained upward trend to fluctuational upward trend,can be divided into moderate increase,quicker increase and upward volatility.Therefore,this paper proposes several policy suggestions:firstly,to improve the monitering of vegetable industry chain and strengthen the guiding role of information flow on the logistics; secondly,to carry out the construction of vegetable market warning system,and minimize the impact of random fluctuations on market caused by unexpected events.Finally,“must attack” measurement for self-production vegetable should be adopted,which can stablize price fluctuations when unexpected events take place.