The invention discloses a method for increasing the purity of carbonyl iron powder, and relates to a method for increasing the purity of the carbonyl iron powder by introducing gas into the common carbonyl iron powder for reduction. The method is characterized in that the process is as follows: reduction treatment is carried out on the carbonyl iron powder under the condition of introducing hydrogen, ammonia or mixed gas of hydrogen and water steam, the reduction temperature is 350 DEG C-850 DEG C, the reduction time is 0.5h-5h, and the use amount of gas is 1.0-50Nm<3> / kg (carbonyl iron powder). In the method for increasing the purity of the carbonyl iron powder, the operation is simple and convenient, the reduction treatment is carried out on the carbonyl iron powder by introducing the gas, detection and analysis are carried out on the obtained carbonyl iron powder, the content of iron in a product is greatly increased, the contents of impurities of carbon, oxygen and nitrogen are obviously reduced, and high-purity carbonyl iron powder is produced. For the carbonyl iron powder treated by the method, the purity is greatly increased, and is increased from 96 percent to more than 98.5 percent.