A new unitarization approach incorporated with chiral symmetry is established and applied to study the piK elastic scatterings. We demonstrate that the K resonance exists, if the scattering length parameter in the 1 = 1/2, J = 0 channel does not deviate much from its value predicted by chiral perturbation theory. The mass and width of the kappa resonance is found to be Mkappa = 594 +/- 79 Mev, GammaK = 724 +/- 332 MeV, obtained by fitting the LASS data up to 1430 MeV. Better determination to the pole parameters is possible if the chiral predictions on scattering lengths are taken into account. (C) 2004 Published by Elsevier B.V.