A method is developed to analyze the in-plane magnetic anisotropy from surface morphology for amorphous films. The lateral sizes along radial direction (R-RD) and tangent direction (R-TD) of rotational substrate, which are extracted from the surface morphology of Co66.3Zr33.7 amorphous films, are used to calculate stress anisotropy energy E-sigma. It is found that E-sigma is consistent with the magnetic anisotropy energy K-mu for the samples deposited on Si (1 0 0) substrate and then a relationship K-mu proportional to 1/R-RD-1/R-TD can be obtained. This method is sensitive to the initial state of substrate so its application range is discussed. (C) 2008 Elsevier B. V. All rights reserved.