Simulation data used in the paper "On the ion distributions at the separatrices during symmetric magnetic reconnection", submitted to Physics of Plasmas. The directory contains the input file, output data and post-processing script from running iPIC3D for investigating the ion dynamics on the separatrices in magnetic reconnection, while the code iPIC3D is available on https://bitbucket.org/bopkth/ipic3d-klm. The data of fields and current can be read through "post-processing.py". For data of particles, there are files describing the data format in each directory. The details are described in the paper.