〔Abstract〕 158 patients with fistula chronic apical inflammation requiring root canal therapy were randomly divided into the experimental group and the control group. In the experimental group, iRoot SP sealant was used for Single-cone obturation technique. In the control group, the root canals were filled with iRoot SP sealant by continuous wave warm vertical condensation. The time of root canal filling, the incidence of postoperative pain at 48 hours and the clinical and X-ray examination results at 1 year were recorded. The root filling time of the experimental group and control group was( 86. 6 ± 12. 1) s and( 138. 6 ± 11. 2) s respectively( P<0. 05). The incidence of pain 48 h after operation in the two groups was 6. 25% and 16. 67%,respectively( P<0. 05). One year after the operation,the effective rates of the two groups were 89. 47% and 92. 00% respectively. Single-cone obturation technique with iRoot SP paste has less postoperative pain response,shorter operation time and more reliable clinical efficacy in the treatment of fistula chronic periapical inflammation. Single-cone obturation technique with iRoot SP paste can be used in the treatment of fistula chronic periapical inflammation.