Indoor self-flowing drainage system on same floor

A same-floor indoor self-flowing drainage system comprises a main drainage pipe laid between adjacent toilets, pipe passing holes are formed in the bottoms of partition walls of the adjacent toilets, the heights of the pipe passing holes are gradually reduced from one side to the other side, and the main drainage pipe is obliquely inserted between the pipe passing holes. The middle lower part of the side wall of each toilet is vertically provided with a pipe pressing piece, the pipe pressing piece is pressed in the middle of the drainage pipe between the two partition walls, and the main drainage pipe corresponding to each toilet is at least connected with two drainage vertical pipes; according to the same-floor drainage system, the height of the pipe passing hole in the bottom of the toilet partition wall is gradually reduced, so that the main drainage pipe is in a micro-inclined state after being installed, sewage can flow automatically and be drained after being drained in, the pipe pressing piece is arran