In this paper, we studied the diagnostic method of DPT using PA method developed by Japanese National Institute of Health (NIH) in 1993-1994, meanwhile we surveyed the antibody level of DPT. We collected 900 sera samples and 300 sera samples from Hebei province in 1993 and 1994. The result showed that PA method was simple, reliable and easy to observe, which can make up the shortages existed in PHA method. The antitoxin titers obtained by the PA method correlated well with the PHA method, while the latter was more sensitive. The antibody level of pertussis obtained through PA method did not correlate well with MA method. The result also showed that the antibody level of DPT was not high, with a 95.0% positive rate of pertussis. The rate of titers higher than 1:320 was 4.7% with GMT 1:121; the positive rate of diphtheria was 62.9% with GMT 0.0280 IU/ml, in 1993 the positive rate of tetanus was 70.5% with GMT 0.1410 IU/ml, in 1994 the positive rate was 75.7% with GMT 0.3281 IU/ml. The titers in urban areas were higher than in rural areas and a decrease was observed with the increase of age. The titers in males was similar to in females. According to this result, a routine immunization followed by booster program should be emphasized.