In order to study the interaction between different systems in the workflow process, the interaction polychromatic graph and interaction matrix of workflow process are constructed based on the polychromatic set theory. Firstly, we combine the tuples and polychromatic set theory to form multi-element binary polychromatic sets and single-element binary polychromatic sets. Secondly, we expand the contour matrix, constituting the K-tuple contour matrix and its disjunction, conjunctive, connected operations, and zone the nodes in the polychromatic graph to represent the resources and messages required for the interaction between the activities. Finally, we construct the interaction model between the system and the workflow process, with the interaction between the hospital HIS and RIS workflow as an example for verification.