The invention relates to a saturated doping process of a thick polycrystalline resistor, comprising the following steps of: a, providing a substrate on which a corresponding oxide structure is arranged; b, depositing a polycrystalline resistor material on the oxide structure of the substrate, and equationally depositing the polycrystalline resistor material for many times according to the required thickness of the polycrystal when depositing the polycrystalline resistor material; c, forming the polycrystalline resistor with the required thickness on the substrate, and then doping phosphorus-including gas in the polycrystalline resistor; and d, removing PSG (Phosphosilicate Glass) formed on the polycrystalline resistor. The thick polycrystalline resistor with the required thickness is obtained by a multiple uniform deposition way according to the thickness requirements of the thick polycrystalline resistor, thus the invention can reduce the stacking of side-products in a furnace and the loss of hardware, such as pumps and the like and improve the stability of the production; in addition, all steps refer to the conventional process, thus the operation is simple; and the polycrystalline doping utilizes the saturated doping so as to make impurities simultaneously diffuse among the crystal grains and the grain intervals, the distribution of the impurities is uniform, and the on-chip and chip-to-chip ranges and the stability are up to the production requirements.