The first non-defocus high transmittance non-fiber image slicer is presented. In order to solve the problem of image blur caused by the defocus between different sliced sub-images, an optical path compensation method based on stepped prism plate is proposed. Design results show that both the maximal defocus amount between the four sliced sub-images is reduced from 2.363 mm to nearly 0. The diameter of the dispersion spot on the focal plane is reduced from 98.47 mu m to close to 0. The optical transmittance of the image slicer is up to 91.89%. This new image slicer is greatly valuable for high resolution and high transmittance spectrometer.