Group B streptococcus (GBS) is a leading cause of invasive neonatal infections and a significant pathogen in immunocompromised adults. Screening pregnant women for GBS colonization can determine whether the pregnant woman needs antibiotic prophylaxis. Therefore, it is crucial to determine the GBS colonization status of pregnant women efficiently and quickly. Here, we set up a point-of-care testing (POCT) according to specific absorption spectroscopy method based on chromogenic culture media to replace the traditional visual identification of GBS. It first converts the bioinformatics (pigment concentration) into light absorption intensity, then transforms the latter into a electrical signal value, and finally computes the electrical signal value into the variable value we defined. In this way, we established a quantitative relationship between the variable value and the GBS concentration, which greatly improved the sensitivity of GBS detection and shortened the identification time of GBS colonization from the traditional 48 h to our POCT’s 6 h as expected.