The invention relates to a composite biological purification wall and a sewage purification pond. The composite biological purification wall comprises a first purification wall body, a second purification wall body and a displacement driving assembly. The first purification wall body and the second purification wall body are arranged side by side in the sewage flowing direction; the displacement driving assembly comprises a driving part arranged on the first purification wall body, a transmission part in driving connection with the driving part and a driven part arranged on the second purification wall body, and the transmission part is transmission matching with the driven part so that the first purification wall body and the second purification wall body can move oppositely to achieve complete overlapping arrangement or partial overlapping arrangement. According to the two overlapping arrangement schemes, the application time of sewage and the composite biological purification wall can be prolonged, so that the sewage is sufficiently purified through the composite biological purification wall, and the effect of purifying and treating the sewage is improved.