The accurate determination of the residual boron content is of great significance to reutilization and the control of treatment cost of the treated fracturing flowback fluid in the oilfield. The composition of the flowback fluid is complex, and the high valence ions will affect the determination results. This work mainly investigated the influence of coexisting ions on measurement of boron content in oilfield fracturing flowback fluid, with the mixed solution of bromocresol green-methyl red-phenolphthalein as the indicator, by using mannitol acid-base neutralization titration. The results show that the optimum range of the method is 30 mg/L~300 mg/L, and the content of Fe3+, Ca2+, Mg2+, SO42-, suspended matter and oil in the fracturing flowback fluid have less effect on the accuracy of the determination results. The relative standard deviation is 0.78 %, and the recovery rate is 99.09 %~100.69 %.