The invention belongs to the metallurgical field, and particularly relates to a method for converting Au+ to Au3+ in the gold smelting process. The method includes the following steps that cyaniding treatment is conducted, and specifically, gold-bearing ore is subjected to cyaniding treatment to obtain an AuCN-containing mixture; activated carbon adsorption is conducted, and specifically, the AuCN-containing mixture obtained in the first step is adsorbed through an activated carbon layer to obtain AuCN-containing gold-bearing carbon; desorption is carried out, and specifically, the AuCN-containing gold-bearing carbon is desorbed to obtain an AuCN desorbed solution; and conversion is carried out, specifically, HCl and Cl2 are added into the obtained AuCN desorbed solution, the reaction temperature is controlled to be 35-55 DEG C, the reaction pressure is controlled to be higher than 5.4 Mpa, and HAuCl4 is obtained after a reaction. By means of the method, the HAuCl4 containing Au3+ can be directly obtained, the technological process is short, the number of adopted devices is small, and the requirements for the devices are low; and energy consumption in the whole reaction process is low, and energy is greatly saved compared with the prior art.