The invention discloses a track harvester hydraulic control system and a control method, and solves the problem of unreliable steering of a paddy machine due to incapability of realizing a steering priority function by a traditional multi-way valve. The track harvester hydraulic control system comprises a main oil inlet, an oil return port, a control valve and a work valve; the control valve comprises a control reversing valve and a priority valve; the control reversing valve is provided with a first position, a second position and a third position; and when the control reversing valve is positioned in the first position and the third position, pressure oil in an oil inlet of the priority valve enters a right side spring cavity of the priority valve through a first throttling hole to cooperate with pressure oil in the oil inlet of the priority valve selected by a left side control cavity of the priority valve for controlling the position of a valve rod of the priority valve. The control method comprises the following steps: when the steering oil cylinder and the work valve are acted, the reversing valve and the priority valve are controlled to realize steering priority actions. Thetrack harvester hydraulic control system has the advantages of simple structure, convenience to assemble, reliable action, long service life and the like.