For the traditional planar two-dimensional grating displacement sensors conducting large-area planar displacement measurements， there were some problems such as complex structure and strict grid processing requirements. A two-dimensional displacement measuring method of "dimension judgment + displacement decoupling" was proposed， which adopted a spatial periodic sensing structure to build the quadrature varying magnetic field mapping between the spatial two-dimensional displacements and time reference. The influences of measuring accuracy on two-dimensional displacements caused by installation errors of the moving scale were studied. Through modeling simulation analysis and experimental verification， the measuring errors of two-dimensional displacement caused by the rolling attitude， the pitch attitude， and the yaw attitude were deeply analyzed.The experimental results show that installation errors mainly introduce DC offset， 2nd and 4th harmonic errors into the two-dimension displacement measurement. When the air gap height between the moving scale and the fixed scale is 0.6 mm， the measuring error in the X direction is not more than ±8.6 μm， the measuring error in the Y direction is not more than ±8.8 μm， and the resolution is 0.15 μm within the 240 mm×240 mm measuring range. The micrometer-level two-dimensional displacement measurement is achieved with millimeter-level sensing units within the 240 mm×240 mm measuring range， which promises the significant academic value and engineering application value.