  The J-PARC linac was consist of 324MHz low-{\beta} section and 972MHz
high-{\beta} section. There is a total of 48 stations. And each station was
equipped with an independent LLRF (Low-Level Radio Frequency) system to realize
an accelerating field stability of $\pm1$% in amplitude and $\pm1${\deg} in
phase. For these llrf system, some of them, especially the 324MHz low-{\beta}
section, had already been used for more than 10 years. Due to lack of supply,
it had become more and more difficult to do the system maintain. And in the
near future, the beam current of j-parc linac was planned to increase to 60mA.
At that time, the current system will face a huge pressure in solving the beam
loading effect. Considering these, a new digital llrf system was developing at
j-parc linac. In this paper, the architecture of the new system will be
reported. The performance of system with a test cavity is summarized.
