Automatic titration and detection method of COD

The invention discloses an automatic titration and detection method of COD. The method comprises the following steps: (1) injecting a sample: quantitatively sucking up all reagents by a sample injection system; (2) carrying out heating digestion: transferring the reagents sucked in step (1) to a digestion return tube (3), and carrying out heating digestion; (3) transferring a digestion solution obtained after the heating digestion is completed to a titration cell, sequentially sucking up quantitative amounts of a color developing agent and distilled water by a micro-fluidic titrating device and allowing the color developing agent and distilled water to enter a digestion tube and enter the titration cell; (4) titrating: allowing lights emitted by an LED light source to pass through the titration cell and be received by a photometric detector, recording data, transmitting the data to a central control system, processing and analyzing the data, and controlling the micro-fluidic titrating device to titrate; and (