The invention provides a bio-filtration treatment device of a causeway of a serial pond. The device comprises a wooden frame (1) as well as a first zeolite layer (2), a first bamboo carbon layer (3), a first soil layer (4), a mixed filter layer (5), a second soil layer (6), a second bamboo carbon layer (7) and a second zeolite layer (8) which are sequentially arranged in the wooden frame (1) from left to right. The device is simple in structure and low in cost and can be modularly assembled. The device is combined by multiple layers and multiple rows according to actual height and width of the causeway and is stably placed according to self weight. Filler or an integral device can be replaced conveniently according to demand or the device is backwashed to be recycled, so that lightly polluted slow flow water bodies such as filtration and treatment runoffs, ponds and the like can be effectively intercepted, and meanwhile, the existing causeway can be fully utilized without occupying additional lands.