Abstract: Infrared absorption spectrum is a better method to detect water oil pollutant. The test result error is minor because of considering the common effect of alkane and sundex. Using the infrared absorption spectrum to measure the oil pollutant content is a good method. This measurement result is not effected by oil types. This measurement method has high accuracy and can be used to detect surface water, underground water, domestic sewage, industry waste and other oil and animal and plant oil material.