The invention discloses an automatic titrator. The automatic titrator comprises a main body casing, wherein a pushing-in groove, a horizontal moving channel and a pushing-out groove are formed in the main body casing, and the pushing-in groove and the horizontal moving channel are sequentially connected to form a right-angle bent channel; a conveying part capable of sliding along a given straight line is arranged in each of the pushing-in groove and the horizontal moving channel, and each conveying part is connected with a corresponding linear driving device. By adopting four actions of entering, exiting, traversing and extending-in, namely, the setting of four displacement directions, the effects of mutual non-overlap between front and back reagent bottles as well as automatic stirring, detection and titration are realized, and no person participates in the whole process, so that the automation degree is high, and pollution is prevented. Step motors cooperate with null electrodes, and the null electrodes divide the whole platform into a pushing-in area, a pushing-out area, a horizontal sliding area and a titration range area corresponding to the pushing-in groove, the horizontal sliding groove and the pushing-out groove, and titration is performed at the mutual overlapped and staggered position of the four areas. Therefore, the error rate is low, and the efficiency is high.