In a method of estimating a PSF in the electron-beam lithography process, a linear resist test pattern may be formed on a substrate. A line response function (LRF) may be determined using a cross-sectional profile of the linear resist test pattern. A development rate distribution in a first direction, the first direction may be substantially perpendicular to an extending direction of the linear resist test pattern, may be calculated using the LRF. A line spread function (LSF), which may represent an exposure distribution in the first direction, may be calculated using the development rate distribution. The PSF may be estimated using the LSF.