It is important that the magnetohydrodynamic (MHD) flow velocity in the cross section of the junction region of a manifold pipe be related to materials compatibility, heat transfer, and MHD pressure drop. Experimental results are given of the velocity distribution across the circular pipe on the center plane in the region of the junction of a manifold pipe and the MHD pressure drop due to the junction MHD effects. The results show that both the boundary layer and core velocity distribution on the center plane of the cross section of the junction region of the manifold pipe increase with an increase of the Hartmann number M and that the velocity at the boundary is jet flow and in the core is flat flow. However, the approach theory expects the core velocity distribution to decrease with an increase of M and never in jet flow at the boundary layer. For the downstream case, the velocity distribution is strongly affected by the junction of the manifold pipe only in a half area of the cross section and for the upstream case in the whole cross-section area. The factor for MHD pressure drops due to the junction MHD effects is also carried out, which explains the experimental data.