Abstract: A heat transfer tube with a cross-grooved inner surface used in refrigerators, air conditioners or the like and a manufacturing method thereof are disclosed. The heat transfer tube is formed in such a manner that the helix angle .alpha. of a primary spiral groove to the longitudinal axis of the tube is in the range of 10.degree. to 40.degree., the intersecting angle .beta. of a secondary groove to the primary spiral groove is in the range of 75.degree. to 105.degree., the ratio H/Hf of a height H of the secondary groove to a height Hf of the primary spiral groove is in the range of 0.5 to 1.0, the slope angle .gamma..sub.1 of an upstream slant face is in the range of 90.degree. to 105.degree. to the direction of the primary spiral groove, the slope angle .gamma..sub.2 of a downstream slant face is in the range of 30.degree. to 60.degree.