Boron in oil field water was directly determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) after sample were treated with nitric acid and filtrated. This method overcomes the problems of spectrophotometry such as long analysis flow, more reagent and difficulty in controlling the chemical procedure. The working parameters and the spectral line were optimized by orthogonal tests. Compared to the method of curcumin spectrophotometry, the method is simpler and faster and the results are more accurate.