Abstract: The high level radioactive wastes disposal R&D in China has stepped into the process of constructing underground research laboratory(URL). In the safety assessment in constructing the URL, and in the performance assessment for the potential geological repository, the diffusion and migration parameters of key radionuclides in corresponding deep geologic environments are needed. While these parameters are strongly related with the species of radionuclides in the corresponding water/rock systems. In order to serve the need in the safety assessment for decommissioning of nuclear facilities, especially the need for performance assessment of potential geological repository, the Nuclear Environmental Chemistry Group of Peking University has been writing a chemical speciation analysis code, CHEMSPEC, since 2008. The code has been modified for several times and currently is available to be used to calculate the speciation of radionuclides in different conditions. This paper introduces the recent development of CHEMSPEC, especially in surface complexation, database improvement, discusses of several calculation cases and the future work of this code.