Zhang, H., Zhang, J., Li, Z., Zhang, J. and Xiao, J., 2017. Improving the imaging resolution of 3D PSTM in VTI media using optimal summation within the Fresnel zone. Journal of Seismic Exploration, 26: 311-330. We improve the amplitude-preserved PSTM in 3D VTI media by introducing a stationary-phase implementation in dip-angle domain so as to achieve optimal summation within Fresnel zone. The previous proposed amplitude-preserved PSTM scheme in 3D VTI media has been proven effective to produce fine image and gathers for hydrocarbon and fluid detection. However, due to the application of a relatively simple migration aperture, this migration scheme may suffer from migration noise and degrade the resolution gained. The proposed implementation in this paper can improve the 3D VTI PSTM by smearing each time sample only along the Fresnel zone rather than along the whole migration aperture, thus suppressing the noises on 3D VTI PSTM result. The Fresnel zone range is defined by picking up dip angles on dip-angle gathers generated from VTI PSTM scheme thus noises outside the Fresnel zones are suppressed in the migration process. The proposed stationary-phase VTI PSTM could effectively solve the problem of low signal-to-noise ratios in migrated images, especially in the presence of steeply dipping structures. We apply the so-called stationary-phase amplitude-preserved VTI PSTM to a field data. An improved imaging result is obtained.