XFEL/SPring-8 employs 72 units of the modulator power supplies for the pulse power klystrons and the electron gun. We took following guide line for our design work: use common component for all klystron power supplies at different frequency ranging from L-band, S-band and C-band, minimize EM radiation from switching thyratron, keep steady operation against environmental temperature and moisture change, compact design, easy handling and suitable for mass-production. To meet all requests, we decided to house all the PFN circuitry and high voltage pulse transformer into a single tank, and filled with insulation oil. Currently, the mass production, and installation are in progress. We expect beam operation before April 2011.