Abstract: Langmuir probe (LP) is a plasma environment detection technology, which is used in a wide range of space-based detection. The LP, as a payload of the China seismo-electromagnetic satellite (CSES), has been designed for in situ measurement of the ionosphere plasma parameters. In this paper, we presented a simplified inversion method of Langmuir probe observation data in the plasma environment, basing on the observation principle of Langmuir probe and the approximate theoretical formula proposed by Irving Langmuir et al. Langmuir probe data tested in plasma chamber is used to verify the method. The results show that the data inversion method is effective and can be used as a basic inversion method of Langmuir probe observation data, which would provide the technical basis for subsequent data processing.