CO2 puff and huff cannot achieve commercial oil productivity for the ultra-deep and low-permeability heavy oil reservoirs at present. The thermal recovery assisted by viscosity reducer and CO2 faces the issues of poor performance of oil viscosity reduction，low productivity of single well and large difficulty of reservoir development. CO2 solubilizing and viscosity reducing system is developed according to molecular system design and experimental verification.In this technology，chemical viscosity reduction and CO2 recovery for the heavy oil are combined to reduce oil viscosity and enhance heavy oil mobility through viscosity reduction effect of chemicals itself and the enhanced ability of CO2 dissolved in oil. The developed CO2 solubilizing and viscosity reducing system can increase the solubility of CO2 by 7 times，and the viscosity reduction ratio is up to 99.2%，which effectively solves the problem of narrow range of oil viscosity reduction for the ultra-deep and low-permeability heavy oil reservoirs. The field application results show that the average daily oil production of the test well is higher than 2.5 times of the original daily oil production，which achieved a good performance.