The utility model discloses a mechanical blocking tee joint for a pipeline, and belongs to the technical field of pipeline maintenance and pipeline emergency maintenance. According to the tee joint, relative movement between the inner walls of a first set of integrated concentric-square slips for the pipeline and the outer wall of the pipeline and relative movement between the inner walls of a second set of integrated concentric-square slips for the pipeline and the outer wall of the pipeline can be prevented, relative movement between the outer walls of the first set of integrated concentric-square slips and the inner wall of a shell and relative movement between the outer walls of the second set of integrated concentric-square slips and the inner wall of the shell can be prevented, and therefore in use, the first set of slips and the second set of slips can prevent relative movement between the mechanical blocking tee joint for the pipeline and the outer wall of the pipeline. Meanwhile, a third channel opening of the mechanical blocking tee joint for the pipeline is formed in an upper shell body, and therefore holes with the diameter equal to the inner diameter of a main pipeline body can be drilled in the main pipeline body in pipeline maintenance or line changing construction. Furthermore, being a mechanical tee joint, the mechanical blocking tee joint for the pipeline does not need to be connected with the pipeline in a welded mode, thereby being applicable to submarine pipelines.