The utility model relates to a desulfurization absorbing tower, comprising an absorbing tower main-body, an original off-gas inlet arranged at the lower-middle part of the absorbing tower main-body, a slurry spraying layer arranged above the original off-gas inlet and at the upper-middle part of the absorbing tower main-body, a demisting device arranged on the upper part of the spraying layer, a clean off-gas outlet arranged on the top of the absorbing tower main-body and an observation device communicated with the part above a normal work level of the absorbing tower main-body. By adopting the technical proposal, not only the operation and level state of the slurry can be directly observed, such as the spraying effects and demisting effect of the slurry in the absorbing tower, but also the observation device can be adopted as a local level meter to directly observe the level in case of a failure of a pressure-difference level meter and to regulate and control the slurry level in time, so as to avoid serious accidents.