To address the problems of low production contribution rate of some clusters and low matching between geological and engineering sweet spot in some shale gas fracturing wells, a new sweetness concept is proposed which is more relevant to production and can make the shortage of sweet spot research perfect. Based on this concept, the concept of fracness is established and calculated by geological sweetness and engineering sweetness, and it can characterize the degree of fracability. Studies and applications show that based on the proposed new concept of geological sweetness and engineering sweetness of shale gas, the concept of fracness and its calculation method are established to evaluate fracability, which enhances the scientific and practicality of fracturing design and specific implementation. The proportion of invalid clusters decreases from 33% to 13%~20%, the average single-well production increased by 35.6%, SRV of one cluster increased by approximately 15% and the fracturing effect is better when fracness is greater than 0.5. It is recommended to further increase the application of shale gas fracness evaluation system, especially in normal pressure and deep shale gas, and to make further improvement and upgrading in the application.