The invention discloses a wastewater treatment device. The wastewater treatment device comprises a shell, a filtering device, a water inlet pipe, a first separation plate, a guiding plate and two first stopping plates; the top of the shell is provided with a flocculant inlet, the bottom is provided with a mud discharging port and a deslagging port, and one side wall is provided with a water outlet; the side wall on the upper part of the filtering device is provided with a plurality of filtering holes, and the bottom of the filtering device is communicated with the deslagging port; the water inlet pipe is connected with the interior of the upper part of the filtering device from one side of the upper part of the filtering device; the bottom of the first separation plate is connected with the bottom of the shell, and the mud discharging port is located between the bottom of the first separation plate and the side wall of the shell provided with the water outlet; the middle part of the filtering device penetrates through the guiding plate, and the flocculant inlet faces the guiding plate; and the two first stopping plates are arranged on the two sides, which are arranged in the widthdirection of the shell, of the guiding plate respectively, and the first stopping plates are perpendicular to the guiding plate, and located above the guiding plate. The wastewater treatment device can effectively separate the impurities in the rainwater, and can save operation energy consumption and cost since no mechanical stirring equipment is arranged, and the impurities in the device can be conveniently removed.