Abstract: Mechanized production engineering mode for major food crops has the similar features as agricultural engineering mode. It is a comprehensive integration of technical factors and non-technical factors, which needs matching and synergy of each element to achieve goals effectively. Mechanized production for major food crops in China has stepped into a critical stage of full mechanization from seed treatment to grain drying, a variety of engineering modes have been formed in the long developing process. With the systems engineering theory, a six-dimensional analytical framework was established, of which the second dimension "mode construction" is the basis of other researches. The mode structure composes of subject (major planter, family farm, cooperative, leading enterprise and ordinary farmers), object (corn, wheat and rice)，demand, objectives, technical route and agricultural machines, which include the full processes of tillage, planting, weeding, fertilizing, plant protection, harvesting, straw treatment and grain drying. An evaluation index system was set up to measure the effect of the mode, and promote the mode to meet the modern agriculture's requirement of high-yield, high-quality, high-efficiency, ecology and safety as well. Based on the principles of scientificity, practicability, guiding, comparability and feasibility, the index system consists of 10 evaluation indices and 4 analysis indices. The advancement, completeness, matching degrees and economic features are taken as the evaluation criteria while the ecological characteristics, integration, policy and organizational features are taken as the analytical indices. The indices are measured from the aspects of mechanized farming rate, operational efficiency, fuel consumption, the implement, farm power, land size, purchasing power of farmers, effect on increasing yield and income, influence to ecological environment, integration of agricultural machinery and agronomy, support policy and organization development. Three rounds of expert anonymous scoring method were used to get index weight. Meanwhile, the combination methods of "modern agricultural development objectives and requirements + statistical data analysis + experience of developed countries and regions + field investigation + expert consultation" were used to get the standard value of each index. In order to test the scientific level of the index system, researchers collected data from different regions in China. And four typical modes of paddy mechanized production in Guangxi, which are "engineering mode of paddy field key processes mechanized production by ordinary farmers", "engineering mode of paddy field key processes mechanized production by small cooperatives", "engineering mode of paddy field key processes mechanized production by medium cooperatives" and "engineering mode of paddy field key processes and post treatment mechanized production by large cooperatives", were selected as the evaluation cases among the various modes. The evaluation results show that the "engineering mode of paddy field key processes and post treatment mechanized production by large cooperatives" has obvious advantages. But at present, the cooperatives set up by farmers can hardly form this mode naturally without government supports in policy, funding, machinery, knowledge and technology because of the deficiency of fund. So to some extent, some measures should be taken by government to guide the appropriate organizations' development and formation of optimization mode, and furthermore to fully play the optimization mode's demonstration and leading roles. The mode construction method and index system are practical and can be improved in practice.