The invention discloses a drainage riser connector of a caisson-type toilet. The drainage riser connector comprises a riser connecting pipe, wherein a lead-in pipe connecting opening is formed in the upper part of the riser connecting pipe; a lead-out pipe connecting opening is formed in the lower part of the riser connecting pipe; the riser connecting pipe is of a structure with an annular waist base extending outwards around the middle section and an annular waist leakage liquid lead-in channel formed on the annular waist base; the annular waist leakage liquid lead-in channel comprises an annular waist leakage liquid collection opening formed in the top surface of the annular waist base, an annular waist leakage liquid lead-in opening which introduced into the riser connecting pipe from the lower part of the annular waist leakage liquid collection opening, and an annular waist leakage liquid diversion cavity connected between the annular waist leakage liquid collection opening and the annular waist leakage liquid lead-in opening; the riser connecting pipe is provided with a diversion baffle for preventing down water from flowing backward into the annular waist leakage liquid lead-in opening in the inner wall corresponding to the position above the annular waist leakage liquid lead-in opening. Compared with the prior art, the secondary drainage problems of drainage caissons at the same layer can be thoroughly solved.