Abstract ToTEM, a multislice‐based image simulation software is developed for transmission electron microscope (TEM). This software implements the following major features: (i) capability of assigning three‐dimensional potentials of atom into multiple slices and precise introduction of phase shift caused by the sub‐pixel atomic position, (ii) employing CUDA coding and graphical processing units (GPU) with multithreading parallel algorithm based on the powerful batch (inverse) fast Fourier transform (FFT), which is especially beneficial for image simulation of scanning transmission electron microscopy (STEM) or (integrated) differential phase contrast (I)DPC, (iii) design for efficiently generating large batch of data set of high‐resolution transmission electron microscopy (HRTEM) images. Image simulation acceleration for STEM has been verified by simulating a large‐scale SrTiO 3 . Additionally, iDPC image of MFI‐type zeolites with xylene molecules encapsulated in straight channels demonstrates the advantage of iDPC in detecting light molecules.