Abstract: In order to adapt to the increasing production efficiency, the existing electromagnetic acoustic thickness measurement system for steel tube needs to be upgraded. On the basis of the preliminary designed transducer with the magnetizer and the testing coils separated, a gas floating designing method for the electromagnetic acoustic thickness measuring transducer is proposed. The gas film formed between the steel tube surface and the agent shoes is used to eliminate the contact friction, so as to realize the full floating servo tracking for the steel pipe. The maximum bearing capacity of the air floatation agent shoes under different eccentricity of the steel tube is obtained through the theoretical calculation. And the electromagnetic acoustic testing equipment with 8 channels was set up to measure the thickness of the steel tube. The accuracy of the measurement results shows that the method is effective. Theoretical analysis and experimental results show that, compared with the traditional method of electromagnetic acoustic thickness measurement for steel pipe, the gas floating designing method can solve the seriously wear problems of a long time contacting with the steel tube, and largely extend the service life of the probe, so as to meet the needs of the steel tube on-line detection preferably.