Spacecraft tends to use combined network of 1553B and SpaceWire to meet the transfer need of both platform management data and payload data. Lots of standard protocols are applied to provide variable and flexible data service, which makes onboard software much more complicated. A protocol set of onboard OBDH software applying combined network of 1553B and SpaceWire is introduced in this article. Based on analysis on the protocols, the software frame as well as the route-table on board is improved. It is proved that the software is much easier to transform and maintain by applying reasonable layer and encapsulation, which can do good to software production as well.