A new matrix well suitable to electroplating diamond bits was proposed. The composition of the plating solution was presented and the hardness and tenacity of the Ni Co Mn coating layer, as well as the Ni Co and Ni Mn coationg layers widely usede for diamond bits, were measured. The results show that Ni Co Mn coating layer has higher comprehensive performance and much lower cobalt content than Ni Co and Ni Mn layers. The Ni Co Mn alloy coating is more suitable to manufacturing the matrix of electroplated diamond bits than the Ni Co or Ni Mn alloy coatings.