The current research on self?injection?locking frequency comb theory is incomplete in exploring the influence of different parameters on self?starting effect. The results of the operating?point locking theory used to explain the locking mechanism and numerical simulation are quite different and cannot explain some experimental phenomena well. Based on the Lugiato?Lefever Equation (LLE) taking into consideration of the backscattering effect, a self?starting Kerr microcomb model is constructed. The influence of key parameters in the model on the self?started locking state of the frequency comb are discussed by using the numerical simulation based on split?step Fourier method and combining the physical connotations of the parameters. Then from the basic formula of the model, the operating?point locking theory is modified to overcome the inadequacies of the self?injection locking micro?comb theory. It is demonstrated that the modified theory can improve the accuracy of the prediction of the locking state in the self?starting numerical simulation, as well as the compatibility between the theoretical prediction and the numerical simulation or experimental results.