The invention relates to an adjustable friction electric separation device and a method for a multi-section type high-voltage electric field. The high-voltage polar plates are arranged in a plurality of sections along the height direction of a sorting cavity, each electrode plate is connected with the outer wall of an adjusting cavity through an adjusting stud, and the high-voltage electrode plates can be adjusted in a horizontal direction relative to a grounding electrode plate; the two adjacent high-voltage electrode plates are connected through a wire, and the high-voltage electrode plates at the bottommost end are connected with high voltage power supply; and when the high-voltage power supply is switched on, an electric field is formed in the sorting cavity between the high-voltage electrode plate and the grounding electrode plate, and when the voltage of the external high-voltage power supply is kept constant, the size of field intensity is inversely proportional to the size of the distance between the high-voltage electrode plate and the grounding electrode plate. According to the device, requirements of the different sizes of the field intensity in the separation process are met, and the equipment cost is reduced; the device can be used for the separation of complex mineral components, plastic particles and metal waste particles, and can also be used for sorting agricultural products and impurities; and therefore the separation efficiency can be improved, the recovery rate of the product can be increased, meanwhile, the situation that the separation electric field is broken down due to the fact that the voltage of the electrode plates arrives the breakdown voltage is avoided, and the stability of the sorting process is improved.