The structure effects of polymers on the relationship between sol fraction and radiation dose are discussed in detail. In consideration of the deviation of experimental results from Charlesby-Pinner's and Chen-Liu-Tang's expressions relating sol fraction to radiation dose, we introduced an exponent β concerned with the structure and property parameters of a polymer (glass transition temperature T,g, and molecular internal rotating steric factor σ) and assumed that the fracture density is proportional to R,β, (R is radiation dose). Thus, a general expression, formula (9), relating sol fraction to radiation dose is derived.,When β=1 and β=0.5, this expression is reduced to the above said two expressions. Using this general expression, the experimental data of a number of polymers are treated. It is shown that the expression is in good agreement with the experimental results. β value is in the range of 0.5 to 1.0.