According to the demand of heat transfer and strength for the erect preheater in power station, a new type of heat transfer enhancement tube, namely the inside and outside triangles finned tube with small spiral angles (IOSF tube), has been developed and manufactured to improve its performance of heat transfer. The field experiment results show that the general heat transfer coefficient of the vertical IOSF tube is 63%~95%, lager than that of the smooth tube. The industrial experiment results show that for a erect high-pressure preheater with IOSF tube, its overall heat transfer coefficient enhances by 43% than the previous. Instead of copper smooth tube, some field and industrial experiments with steel spiral groove tube have also been carried out. The results show that the preheater with steel spiral groove tube not only guarantees the heat load, but also can improve its performance of heat transfer to meet the demand of no copper in water entering into boiler.