The METeorological Pictures Autocreating System (MEPAS) is an operational automatic plotting system of meteorological charts being close to the operational data environment, which supports several data formats, such as GRIB1/GRIB2, includes many algorithms on calculating meteorological variables and convection indexes, and supports mesoscale analysis. MEPAS runs on command lines by writing Analogue scripts in XML files, being easy to learn, convenient to use, running steadily and effectively. It is designed for the meteorological operational system and the relative research programs, and can be used in the nextgeneration MICAPS, filling the gap of MICAPS script technique.