A method for processing acetic acid solvent in an oxidising unit of a PTA industrial apparatus, comprising the following steps: conveying CTA slurry containing acetic acid to a filtering area of a pressure filter to separate solid particles and acetic acid in the CTA slurry so as to form a CTA filter cake, separated mother liquor, and residual liquid in a filtrate pipe, and then conveying the CTA filter cake to a first washing area of the pressure filter following a rotation of the pressure filter, discharging the separated mother liquor to a mother liquor tank, and biasing the residual liquid in the filtrate pipe to the mother liquor tank; conveying primary washing liquid in a primary washing liquid tank to the first washing area to perform a first stage of washing on the CTA filter cake, and then conveying the CTA filter cake processed by the first stage of washing to a second washing area of the pressure filter, conveying the primary washing liquid to a recycling washing liquid tank and biasing the residual liquid in the filtrate pipe to the primary washing liquid tank after the first stage of washing; conveying secondary washing liquid in a secondary washing liquid tank to the second washing area to perform a second stage of washing on the CTA filter cake, and then conveying the CTA filter cake processed by the second stage of washing to a third washing area of the pressure filter, conveying the secondary washing liquid to the primary washing liquid tank and biasing the residual liquid in the filtrate pipe to the secondary washing liquid tank after the second stage of washing; and washing the CTA filter cake stage by stage through a plurality of washing areas sequentially in a similar manner as above, until the CTA filter cake processed by the (n-1)th stage of washing is conveyed to the nth washing area of the pressure filter, conveying external process water to the nth washing area to perform the nth stage of washing on the CTA filter cake, and then conveying the CTA filter cake processed by the nth stage of washing to an unloading area of the pressure filter so as to be mixed and pulped with the external process water, conveying the nth washing liquid to the (n-1)th washing liquid tank, and conducting the residual liquid in the filtrate pipe to a filtrate tank and further conveying it to the (n-1)th washing liquid tank, after the nth stage of washing. conveying CTA slurry containing acetic acid to a filtering area of a pressure filter to separate solid particles and acetic acid in the CTA slurry so as to form a CTA filter cake, separated mother liquor, and residual liquid in a filtrate pipe, and then conveying the CTA filter cake to a first washing area of the pressure filter following a rotation of the pressure filter, discharging the separated mother liquor to a mother liquor tank, and biasing the residual liquid in the filtrate pipe to the mother liquor tank; conveying primary washing liquid in a primary washing liquid tank to the first washing area to perform a first stage of washing on the CTA filter cake, and then conveying the CTA filter cake processed by the first stage of washing to a second washing area of the pressure filter, conveying the primary washing liquid to a recycling washing liquid tank and biasing the residual liquid in the filtrate pipe to the primary washing liquid tank after the first stage of washing; conveying secondary washing liquid in a secondary washing liquid tank to the second washing area to perform a second stage of washing on the CTA filter cake, and then conveying the CTA filter cake processed by the second stage of washing to a third washing area of the pressure filter, conveying the secondary washing liquid to the primary washing liquid tank and biasing the residual liquid in the filtrate pipe to the secondary washing liquid tank after the second stage of washing; and washing the CTA filter cake stage by stage through a plurality of washing areas sequentially in a similar manner as above, until the CTA filter cake processed by the (n-1)th stage of washing is conveyed to the nth washing area of the pressure filter, conveying external process water to the nth washing area to perform the nth stage of washing on the CTA filter cake, and then conveying the CTA filter cake processed by the nth stage of washing to an unloading area of the pressure filter so as to be mixed and pulped with the external process water, conveying the nth washing liquid to the (n-1)th washing liquid tank, and conducting the residual liquid in the filtrate pipe to a filtrate tank and further conveying it to the (n-1)th washing liquid tank, after the nth stage of washing.