Abstract: Changqing upper-palaeozoic gas reservoir is a kind of reservoir with low physical characteristics, low pressure modulus and strong water lock. The work fluid flowing back is very difficult and gas well production is low after general hydraulic fracture technique was used. Based on reservoir betterment and geology research, tackle key problem indoor to CO2 fracture technology, introduced and developed acidity crosslink technique, optimize CO2 fracture design and locale construct technique. Via locale use, it shows that CO2 add-energy-fracture is an efficiency fracture technique, it is good for improving single well output and whole development level of Changqing gas field.