The invention discloses a process and equipment for preparing biogas by continuous mode dry fermentation. The process comprises the following steps of: mixing various green materials (animal manure, straw, organic waste and the like) uniformly, delivering into a fermentation tank, feeding and discharging once per day, recovering 25-35% of discharged materials into a stirrer and mixing with green materials uniformly, and heating the percolate in the fermentation tank through a spray pump by a heat exchanger and then spraying into a reaction tank. The major equipment comprises a storage bin, a measuring belt, a gathering belt, a screw feeder, a stirrer, a feed screw, an elevator, a feeder, a fermentation tank, a gas reservoir, a biogas outlet tube, a spray tube, a heat exchanger, a spray pump, a discharge screw, a gathering screw, a discharging machine, a recovery screw, a flow-dividing screw, a control system and the like.