The invention discloses a longitudinal automatic net laying and connecting device and method for a bottom plate of layered mining of thick coal seams. The longitudinal automatic net laying and connecting device comprises a first hydraulic support and a second hydraulic support which are arranged in parallel, wherein a first rear seat is arranged at the tail part of the first hydraulic support, anda second rear seat is arranged at the tail part of the second hydraulic support; a first intra-frame net roll is further arranged on the first hydraulic support, and a second intra-frame net roll isfurther arranged on the second hydraulic support; a first net is wound around the first intra-frame net roll, and a second net is wound around the second intra-frame net roll; and an automatic net laying and connecting mechanism is further arranged between the first hydraulic support and the second hydraulic support, the automatic net laying and connecting mechanism comprises an inter-frame net laying unit, a pushing unit and a net connecting unit, the inter-frame net laying unit is used for installing or spreading a third net which is wound, and the pushing unit is connected with the inter-frame net laying unit. According to the longitudinal automatic net laying and connecting device, the nets can be automatically laid on the bottom plate and connected in the layered mining process of thethick coal seams, the workload of underground workers is reduced, and the net connecting efficiency is improved; and the automatic net laying and connecting device is high in operability and practicability.