Manufacturing method for gradient cemented carbide matrix of diamond coating

The invention relates to a manufacturing method for a gradient cemented carbide matrix of a diamond coating. The method includes the steps that a, carbon-depleted cemented carbide not containing the eta phase overall is manufactured; b, the carbon-depleted cemented carbide is ground to form a tool; c, gas carburizing surface treatment is performed on the tool; and d, the carburized tool is polished, chemically corroded and ultrasonically washed, so that the gradient cemented carbide matrix of the diamond coating is obtained. The gradient cemented carbide matrix of the diamond coating is manufactured through the method, the Co content of the surface is low, the adhesive force of the diamond coating is large, the Co content of the core is high, no eta phase exists, tenacity is good, and the manufactured diamond coating tool is good in cutting performance and long in service life; and the diamond coating can be manufactured through conventional methods such as a microwave plasma CVD method and a heater CVD method for the gradient cemented carbide matrix, and a diamond coating device and a diamond coating process do not need to be improved.