A new quantitative method to determine the NH4H2PO4 in ABC powder extinguishing agent and to distinguish between ABC and BC powder extinguishing agents using near infrared diffuse reflectance spectroscopy is proposed. A PLS calibration model for the NH4H2PO4 content in extinguishing agent powder was established, with RMSECV=2.1, RMSEP=2.4. An identification model for ABC and BC powder extinguishing agents was built by SIMCA and the identification accuracy rate is 100%. This method, compared to the present standard method, has the characteristics of rapidness and easy operation, whichis fit for the quantitative analysis and type distinguishing of the fire products on site.