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Whole plastic mulching and furrow planting has been widely adopted as a drought resistant cultivation model in the northwest arid area of China in recent years. For further integration agronomic requirement of whole plastic-film mulching on double ridges, in order to realize the mechanized construction of seedbed, a combined operation machine was designed, which synchronously realized institutional operation once such as fertilization, ridging, filming, infiltration hole punching and girdle covering on double ridges. Based on the prototype, the key parts were designed and selected, the structure and operation parameters of soil elevating mechanism and pressing-punching mechanism were determined, and the power consumption of rotary blades was calculated. The operation process of soil transporting-covering mechanism and girdle soil covering mechanism were analyzed, and the necessary work conditions to make sure that the covering soil on the all parts of the seedbed were analyzed and calculated. For the relevant work performance test of prototype, the field experimental results showed that under the condition of the operation speed of 0.50m/s, the mechanical damage degree of day lighting surface of plastic film was 38.6mm/m2, the qualified rates of ridging height was 89.8%, the qualified rates of furrow center distance was 90.7%, the qualified rates of soil width covered on seedbed film edge was 95.8%, the qualified rates of girdle covering soil width was 95.6%, the qualified rates of soil depth covered on seedbed was 95.2%, the spacing qualification rate of girdle covering soil was 93.5%, and the spacing qualification rate of water-leaking hole was 97.1%, which met the relevant work quality evaluation specification requirements, and the experimental results also met the design requirements of combined operation machine.