The whole rectification process is used to produce argon in air separation plant, which is to separate oxygen from argon in crude argon column, and directly obtain crude argon with oxygen content less than 1 × 10-6. Then argon nitrogen separation is carried out in refined argon to obtain purified argon product with purity of 99.999%. More and more argon production unit of air separation adopts the process of hydrogen free argon production to produce high purity argon products.