According to the practical problems in eddy current sorting, the method and technology of eddy current hardness sorting based on Least Squares Support Vector Machine (LS-SVM) are proposed based on the Xilinx Artix-7 FPGA in this paper. The calculated sort-ing-hyperplane and designed sorting decision-making machine were used to sort different hardness of the vavles. The experimental results of the vavle sorting show that the sorting success rate can reach 100% under conditions that the number of test vavles is one quarter of the training vavles. The method and technology based on LS-SVM can solve the problems that the impedance feature value is nonlinear with the hardness value and variable sorting interval. It also proved that the LS-SVM algorithm has strong practical value in online eddy current sorting.