A six degrees of freedom rigid body dynamics coupled numerical simulation model under dynamic grid was established, and the passive rotation process of the propeller caused by water impacting the frame-type current meter was simulated. It was based on the Navier-Stokes equation for incompressible fluid flow and the SST k-ω turbulence model, combined with the VOF multiphase flow model. This was done to analyze the flow field characteristics and motion posture of the frame-type current meter in the open channel, while calibrating the multiplier constant K and friction coefficient C. In this way, this can analyze the influence of different positions of the current meter on the multiplier constant K and friction coefficient C. The results showed that the use of the dynamic grid 6DOF model can effectively simulate the flow state of the frame-type current meter in open channels, and the simulation results were highly reliable. By analyzing the fitting curves of rotational speed and flow velocity at different times, it can be concluded that the different positions of the current meter would affect the magnitude of the friction coefficient C of the current meter, and it had little effect on the multiplication constant K of the current meter. This achievement can provide theoretical basis and technical support for the construction of digital twin irrigation areas and the measurement of open channel water in irrigation areas. The research results can provide necessary references for further research on the optimization of frame-type current meter and the wear of current meters under different sediment flow conditions.