To detect infant complementary food supplements of folic acid, methds of microbiological method, solid-phase-extraction-HPLC and direct-ammonia-extraction-HPLC were utilized respectively. Analyses among the three methods were compared and the most accurate and rapid one was determined. The results showed the direct-ammonia-extraction-HPLC analysis by using the CH3OH-0.05 mol/L KH2PO4 (volum ratio,5∶95; pH 6.3) as mobile phase and controlling the peak time at 6.5 min, and the standard curve coefficient was 0.999 8 with detection limit 0.019 0 mg/L. Compared with the other two methods, this method was simple, rapid, sensitive and reproducible characteristics, and provided an effective theoretical basis to establish method of folic acid detections in infant complementary food supplements.