Cereal crops are at the forefront of the main agricultural crops in the crop composition in Egypt because of their high nutritional and economic importance in achieving Egyptian food security. It also influences the Egyptian political decision. Therefore, the study aims to measure the impact of changes in agricultural policies on the production value of the most important cereal crops in Egypt during the period (1980-2016). To achieve the objectives of study the method of decomposition of heterogeneity and annual growth rates have been used. The most important results of study can be summarized as follows: (1) the impacts of the individual and the joint changes on production values of wheat, rice and maize are decreased during the first three periods and the fifth period of the studied period: period before economic liberalization (1980-1986), the transitional period (1987-1991), the structural adjustment policy period (2003-2010) and the period after 25 Januray revolution (2011-2016). On contrast, the individual and the joint changes on production values of the studied crops are increased in the fourth period; the period before 25 January revolution (2003-2010). (2) The effects of non-price changes on production values of wheat and rice are increased during the first three periods of the studied period and then are decreased in the fourth period and then are increased again in the fifth period. (3) The fluctuation of the effects of individual and joint non-price changes on production values between rise and fall during fifth studied periods for maize. (4) The annual growth rate of the farm-gate prices followed by the productivity then the cultivated areas for three studied crops during the studied period have been increased gradually.