[3] He thus served, from 1949 to 1959, as an administrative employee in the Legislative Bureau of the Central People's Government, the Political and Legal Commission of the Central Committee of the Chinese Communist Party, the State Council Bureau of Legislative Affairs, as well as the State Council's General Office.
In 1959, he served as Section Chief and then Director of the Department of Legal Affairs of the China Council for the Promotion of International Trade.
[6] Restored to his position in 1971, from that year to 1981 he was the Director of Legal Affairs in the China Council for the Promotion of International Trade (CCPIT), and, importantly, Secretary-General in its Maritime Arbitration Commission.
This position became significant with the start of the Chinese economic reform, and Ren dealt with globally key maritime players, such as Greek ship-owners.
In November 1973, Ren Jianxin headed a Chinese Government delegation, including Lu Long, Wang Zhengfa, and Yang Bo, to Geneva as an observer for the Fourth Series of Meetings of the Governing Bodies of the World Intellectual Property Organization (WIPO).