The invention provides a double-membrane soil pressure sensor based on hydraulic transmission. The sensor employs a double layer membrane structure. A primary membrane is bonded with an outer ring of a housing by an annular membrane at an edge; and a secondary membrane is welded on an inner ring of the housing. An oil nozzle is used to enable a pressure transmission oil chamber formed between the primary membrane and the secondary membrane to be filled with hydraulic oil. A strain probe that is arranged below the secondary membrane and has a sensing element is connected with an external transmission line by a lead-out hole that is reserved and is arranged inside the housing; an epoxy resin is used for sealing the lead-out hole; and the housing and a bottom cap are threadedly connected. Therefore, a double-membrane soil pressure sensor based on hydraulic transmission is formed. According to the invention, influences caused by uneven distribution of soil pressures and difference of soil texture kinds can be eliminated; adaptability is strong; and calibration can be carried out simply.