The invention provides a liquid caustic soda and caustic soda flake simultaneous production apparatus, which relates to the field of chemical production apparatuses. The production apparatus comprisesa first caustic soda groove communicated with an effect-I falling film device, wherein the effect-I falling film device is communicated with an effect-II falling film device, the effect-II falling film device is communicated with an effect-III concentrator by virtue of a first heat exchanger, the effect-III concentrator is communicated with a caustic soda flaker; a first valve is arranged betweenthe effect-II falling film device and the first heat exchanger, the effect-II falling film device is communicated with a third heat exchanger by virtue of a second valve and a second heat exchanger,and an output pipeline of the third heat exchanger is provided with a third valve; one end of a pipeline mixer is communicated with the second heat exchanger, and the other end is communicated with the first caustic soda groove; a pipeline communicated with a second caustic soda groove is arranged between the output end of the third heat exchanger and the third valve; and a fourth valve is arranged between the output end of the third heat exchanger and the second caustic soda groove, and the second caustic soda groove and a third caustic soda groove are communicated with each other to be communicated with an output pipeline by virtue of the third valve. The apparatus can simultaneously produce the liquid caustic soda and the caustic soda flake, so that the frequent switching of a liquid caustic soda mode and a caustic soda flake mode can be avoided, the production stability is facilitated, and the production cost is saved.