The invention relates to a high-purity chlorine gas rectifying technology. The technology comprises the following steps: delivering industrial liquid chlorine to a vaporizer, and sending vaporized chlorine into a first distillation tower under the pressure of 1.2 Mpa until the liquid level of the first distillation tower reach 85%; boosting the pressure of the first distillation tower to 1.0 Mpa, condensing the vaporized chlorine by a first condenser, then sending into a first reflux tank, and delivering 60% residue in the first reflux tank to a second distillation tower; enabling the liquid level of the first reflux tank to be 30% to 40%, and boosting the pressure of the second distillation tower to be 1.8 Mpa; back flowing residue condensed by a second condenser in to the second distillation tower, then sending into a third distillation tower, controlling the liquid level of the second distillation tower to be 60% to 75% until the liquid level of the third distillation tower reaches 85%, and boosting the pressure of the third distillation tower to be 1.5 Mpa; condensing by a third condenser, then sending into a third reflux tank until the purity reaches 99.9999%, enabling the liquid level of the third reflux tank to reach 60%, enabling the purity of the liquid chlorine in the third reflux tank to be 99.9999%, and obtaining high-purity chlorine gas. Through the adoption of the method, raw material input and product output can be carried out stably and continually, the production capacity can be improved, energy consumption can be reduced through continuous rectification, the running is stable, and the operation is safe.