The China Seismo-Electromagnetic satellite (CSES) was designed to study the ionospheric disturbances associated with earthquakes. Satellite payload includes nine instruments. Among them, we recall instruments for plasma analysis, electric, magnetic fields and high energy particle detectors. Langmuir probe (LP) and plasma analyzer package (PAP) are the in-situ payloads to measure space plasma. Its scientific objective is to research space plasma physics phenomena and the ionosphere changes caused by seismic. It is the first application of in-situ measurement technology in the field of space exploration in China. The Langmuir probe and Plasma Analyzer Package have been tested and calibrated to verify the performance in INAF-IAPS. Currently, on-orbit testing is being performed with satellites. © 2018, Science in China Press and Springer-Verlag GmbH Germany, part of Springer Nature.