<p>We construct a series of vortex patch solutions in a doubly-periodic rectangular domain (flat torus), which is accomplished by studying the contour dynamic equation for patch boundaries. We will illustrate our key idea by discussing single-layered patches as the most fundamental configuration and then investigate the general construction for <i>N</i> patches near a point vortex equilibrium. Unlike the case of bounded domains in <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\mathbb {R}^2\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>, a constant background vorticity will arise from the compact nature of a flat torus, and the two-dimensional translational invariance will cause trouble in determining the patch locations. To overcome these two difficulties, we will add additional terms for background vorticity and introduce a centralized condition for the location vector. By utilizing the regularity difference of terms in contour dynamic equations, we also obtain the <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(C^\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>C</mi> <mi>∞</mi> </msup> </math></EquationSource> </InlineEquation> regularity and convexity of the boundary curves.</p>