In this study, the interaction between the main crack and secondary crack was investigated using the Reduced XFEM, which is constructed with a new type of crack tip enrichment function. The effect of the secondary crack on the stress intensity factor(SIF)of the main crack was studied, and the SIF was calculated with the interaction energy integral method at crack tips. The calculation results show that the existence of the secondary crack decreases the SIF of the main crack. The SIF of the main crack decreases significantly with the increasing length of the secondary crack. The changes of the distance from the main crack to the secondary crack and the SIF of the main crack follow certain rules: the SIF of the main crack shows a scoop-shaped distribution as the distance increases, and it changes insignificantly, being close to a single crack state, as the distance reaches a certain value.