Abstract: In order to fill the blank of contractile strain ratio testing of metal materials tubing, some companies were responsible for drafting of GB/T 34645—2017 Contractile Strain Ratio Testing of Metal Materials Tubing. The compilation principle, main technical indicators and differences from foreign standards were described in detail. Compared with similar foreign standards, GB/T 34645—2017 has added principle description, measurement standard consistency requirements, and elastic hysteresis phenomenon description. It can fully meet the requirements of contractile strain ratio testing of metal materials tubing for domestic aerospace, aviation and nuclear metal tube products.