Based on the feature of the ELID grinding, heat production mechanism in the ELID grinding was analyzed and a heat source model was given. Heat partition among work-piece, grinding wheel and electrolyte was discussed and a heat partition model was established. And numerical investigation was down. The results indicated that heat in ELID grinding was mainly produced by interaction between grit and work piece. Partition of the heat among work piece, grinding wheel and electrolyte was function of position. Electrolyte and grinding wheel take away the most heat produced in ELID grinding.