Abstract: A piecewise integration conformal finite difference time domain(PI-CFDTD)method is presented and applied for solving the electromagnetic scattering problems.The electric field component along the contour segment is expressed by the interpolation of the nearest ones.To compute electric-field contour-integral value more accurately,the piecewise-integration method is used instead of the common integration.Therefore,the staircasing errors can be reduced significantly.The electric-field contour-integral formula is derived for two kinds of deformed cells,respectively.Furthermore,the numerical stability is discussed.Finally,a metal square plate and a metal circular plate are simulated as examples.The results are compared with those of the conventional FDTD method CFDTD method and the MoM.It is found that the PI-CFDTD method is more accurate than the conventional CFDTD method.