The invention provides a video acquisition device and system used for remote teaching, and a direct broadcast method. The device includes a first camera, a second camera, a third camera, a fourth camera, a first A/D chip, a second A/D chip, a third A/D chip, a fourth A/D chip, a first encoder, a second encoder, a third encoder, a fourth encoder, an FPGA chip and a tetrahedral installation rack; and the first camera, the second camera, the third camera and the fourth camera are separately arranged in the center of each of the four faces of the tetrahedral installation rack. The video acquisition device and system used for remote teaching, and the direct broadcast method collect different video data through the four cameras, obtain the video data with different definition after video conversion, and send the video data with different definition to different users, so that video playing can be safer and more fluent, and user demands can be met.