A stacking modular instrument bus device includes N instrument sub-modules, N+1 customized bus connectors, a first bus termination module and a second bus termination module. The N instrument sub-modules are connected with each other in series through the N−1 customized bus connectors to form an instrument sub-system, two ends of the N instrument sub-modules are respectively connected with the first bus termination module and the second bus termination module through one customized bus connector; each of the instrument sub-modules includes a bus unit and a functional unit. The present invention can freely stack and combine all the instrument sub-modules in the manner of building blocks, which is divorced from the conventional backboard type structure and becomes more flexible. Every instrument sub-module has the independent and complete instrument structure and form the system itself. The bus unit of the instrument sub-module is detached from the functional unit thereof.