We report on the saturation magnetostriction coefficient of 500 angstrom (Co82Cr18)(100-x)Pt-x and x angstrom (Co82Cr18)(79)Pt-21 alloy thin films with perpendicular magnetic anisotropy. The CoCrPt alloy films were prepared by dc magnetron sputtering and the magnetostriction coefficients were measured via a highly sensitive optical deflection-detecting system using a one-dimensional position sensitive detector. The saturation magnetostriction coefficient is increased from -7.23 X 10(-6) to 8.5 X 10(-6) and from -8 X 10(-6) to 14 X 10(-6) with increasing the Pt concentration from 0 to 35 at. % and the film thickness from 400 to 800 angstrom, respectively. X-ray diffractometry study revealed that crystalline orientation in CoCrPt alloy film, which depends on the Pt concentration and the CoCrPt film thickness, strongly influences the evolution of saturation magnetostriction coefficient. (c) 2005 American Institute of Physics.