The invention discloses an electric seat one-key adjusting system and method. The electric seat one-key adjusting system comprises a seat adjusting control unit, a seat front-back sliding switch and aseat front-back sliding motor, wherein the foot positions 1 and 2 of the seat adjusting control unit are respectively connected with a normal electricity and an IG electricity of a vehicle; the footposition 9 of the seat adjusting control unit is connected with the negative pole of a storage battery of the vehicle; the foot positions 7 and 8 of the seat adjusting control unit are respectively connected with the seat front-back sliding motor t in a control way; the foot positions 3 to 6 of the seat adjusting control unit are respectively connected with automatic forward shifting, manual forward shifting, manual backward shifting and automatic backward shifting of the seat front-back sliding switch. When the electric seat is adjusted, the electric seat can be automatically moved by one key, and manual fine adjustment is carried out after the electric seat is close to a comfortable area of a driver or an occupant, so that the comfortable feeling of the driver or the occupant when the seat is adjusted can be improved; meanwhile, the automatic movement of one key can be convenient for the seat to move up and down in a large range and a backrest to fall down and lift, thereby greatly facilitating the adjustment of the seat by the driver or the occupant.