The invention provides a method for measuring the modifier content of SBS (styrene butadiene styrene) modified asphalt. The method comprises the following steps of preparing a series of standard modified asphalt samples with different SBS contents, measuring the redox potential of the SBS modified asphalt through a potentiometric titrator, performing data processing, and constructing a math model showing a relation of the SBS modifier content and an iodine value. According to the method aiming at the problem that the quality of products in a modified asphalt market is uneven and no direct detection measure is provided, the SBS content is measured by introducing a potential method; data are obtained by using a precision instrument, so that high repetitiveness is achieved; common SBS modified asphalt, high-viscosity high-elasticity modified asphalt, SBS modified emulsified asphalt and SBS-containing colored asphalt adhesives can be measured; personal errors are reduced; meanwhile, the workload is reduced, and the detection efficiency is improved.