  Taiji-1 is the first technology demonstration satellite of the Taiji program
of China's space-borne gravitational wave antenna. After the demonstration of
the key individual technologies, Taiji-1 continues collecting the data of the
precision orbit determinations, satellite attitudes, and non-conservative
forces exerted on the S/C. Therefore, during its free-fall, Taiji-1 can be
viewed as operating in the high-low satellite-to-satellite tracking mode of a
gravity recovery mission. In this work, we have selected and analyzed the one
month data from Taiji-1's observations, and developed the techniques to resolve
the long term interruptions and disturbances in the data due to the scheduled
technology demonstration experiments. The first global gravity model
\texttt{TJGM-r1911}, that independently derived from China's own satellite
mission, is successfully built from Taiji-1's observations. Compared with
gravity models from CHAMP and other satellite gravity missions, the accuracy
discrepancies exist, which is mainly caused by the data discontinuity problem.
As the extended free-falling phase been approved, Taiji-1 could serve as a
gravity recovery mission for China since 2022 and it will provide us the
independent measurement of both the static and the monthly time-variable global
gravity field.
