In this work, novel photocatalysts Ag3PO4@MWCNTs@PANI with excellent visible light photocatalytic performance and photostability were successfully prepared by a facile in-situ precipitation method. The optimal catalyst [email protected]%MWCNTs@3%PANI showed the highest photocatalytic performance for degradation of phenol and p-nitrophenol, the apparent rate constant of which was 21.9 and 10 times than that of the pure Ag3PO4, respectively. Interestingly, the Ag3PO4 exhibited significant changes in particle size, which changed from 10 to 20 gm for pure Ag3PO4 particles into 0.38-1.0 pm and 0.15-0.38 tim with the addition of MWCNTs and PANI, respectively. In presence of MWCNTs, similar phenomena have been reported in our previous studies, while the ability of PANI dissolved in the presence of DMF solvent to control the size of Ag3PO4 crystal was reported for the first time. The dramatic enhancement of photocatalytic activity and photostability could be attributed to the synergetic effect between MWCNTs and PANI on Ag3PO4. The MWCNTs penetrating in the bulk phase of Ag3PO4 could serve as conductors of photogenerated electrons and rapidly migrated electrons to the surface of the photocatalysts. Meanwhile, photogenerated holes in the valence band of Ag3PO4 were transferred to the photocatalysts surface through HOMO of PANI. Consequently, high separation efficiency of electron-hole pairs was successfully achieved. A novel design and preparation strategy for photocatalyst was proposed to simultaneously achieve the small size control of catalyst crystal and improve the photocatalytic performance of catalyst by adding MWCNT and PANI.