The Common Agriculture Policy (CAP) reform in 2003 decoupled the farm pay- ments from production, the 2014-2020 reform decides a shift of direct payments from land to active farms. In order to study the impact of the CAP reforms on farmers' production, consumption and investment decisions, we develop a stochastic dynamic farm model with price risk and productivity risk. We structural-estimate the model's deep parameters, in particular, the risk preference parameter, using particle lter and MCMC method. The solution of the model shows that the representative farmer's de- cision rules on consumption and investment vary with dierent risk preferences. We expect a change of the farmer's risk aversion level before and after CAP reform. How- ever, due to the quality of data and the in developing non-linear ltering technique, the crucial deep parameters are not statistically identied.