Biochemical oxygen demand tacheometer with automatic liquid flow path switching device

The utility model discloses a biochemical oxygen demand tacheometer with an automatic liquid flow path switching device, which is characterized in that a measuring groove is connected with a peristaltic pump via a pipeline and injects samples continuously, a biosensor which is arranged in the measuring groove is connected with a main control board signal chip microcomputer, the peristaltic pump is connected with the automatic liquid flow path switching device consisting of a plurality of electromagnetic valves, each electromagnetic valve is connected with each corresponding liquid tank, a single chip microcomputer starts or stops at least one electromagnetic valve according to preset procedures, biochemical oxygen demand of to-be-measured solution is measured via a sensing signal of the biosensor, a heating bar, an air pump, a key board, a display and a printer are further connected between the peristaltic pump and the measuring groove, wherein the heating bar heats the to-be-measured solution in constant tem