This paper was aim to determine five phenolic acids, sodium danshensu (SD), protocatechuic aldehyde (PA), rosmarinic acid (RA), lithospermic acid (LA) and salvianolic acid B (SAB), in Guanxinning injection. In the test, Kromasil C18 column (4.6 mm x 250 mm, 5 µm) was adopted, with acetonitrile-3% formic acid solution as the mobile phase for gradient elution. The flow rate was 1 mL · min, the column temperature was 30 °C and the detection wavelength was 280 nm. According to the results of the test, SD, PA, RA, LA and SAB showed good linear relations between peak areas and sample sizes in 0.006 06-4.04 (r = 0.999 3), 0.006 15-4.10 (r = 0.999 4), 0.005 94-3.96 (r = 0.999 3), 0.006 06-4.04(r = 0.999 1) and 0.006 09-4.06 (r = 0.999 2) µg, respectively. The average recoveries (n = 6) were 98.9% (RSD 0.75%), 98.1% (RSD 1.2%), 100% (RSD 0.77%), 98.7% (RSD 1.7%), 102% (RSD 0.68%), respectively. The above 5 components were determined in 13 batches of samples by using the established method. The method was simple, accurate and highly reproducible that it could be used for quality control of the components in Guanxinning injection.