The invention relates to an infrared-spectroscopy ATR determination method for the contents of microstructures in solution-polymerized styrene butadiene rubber. The method comprises the following steps: acquiring the contents of styrene, 1,4-trans-polybutadiene, 1,2-vinyl-polybutadiene and 1,4-cis-polybutadiene at first; then measuring the absorbance of the above four microstructures in standard substances through infrared-spectroscopy ATR determination so as to obtain constant coefficients a1 to a4 and k1 to k4; and establishing quantitative calculation formulas (I) to (IV) and calculating the contents of the four microstructures, wherein the formula (I) is that the content of styrene is equal to the product of 100 and the mean value of C, C, C and C; the content of 1,4-trans-polybutadiene is equal to the product of 100 and the mean value of C, C, C and C; the content of 1,2-vinyl-polybutadiene is equal to the product of 100 and the mean value of C, C, C and C; and the content of 1,4-cis-polybutadiene is equal to the product of 100 and the mean value of C, C, C and C.