A 2-Q antiferromagnetic order of the ferromagnetic dimers was found belowTN= 2.9 K in the Shastry-Sutherland lattice BaNd2ZnS5by single crystal neutron diffraction. The magnetic order can be understood by the orthogonal arrangement of local Ising Nd spins, identified by polarized neutrons. A field was applied along [1 -1 0] to probe the observed metamagnetic transition in the magnetization measurement. The field decouples two magnetic sublattices corresponding to the propagation vectorsq1= (½, ½, 0) andq2= (−½, ½, 0), respectively. Each sublattice shows a “stripe” order with a Néel-type arrangement in each single layer. The “stripe” order withq1remains nearly intact up to 6 T, while the other one withq2is suppressed at a critical fieldHc~1.7 T, indicating a partial disorder. TheHcvaries with temperature and is manifested in theH-Tphase diagram constructed by measuring the magnetization in BaNd2ZnS5.