In order to improve the performance of polyethylene (PE) products without changing the existing process of film blowing, casting, extrusion, low dose γ irradiation was carried out to realize the micro-crosslinking of linear low-density polyethylene (LLDPE) materials in this work. The effects of low absorbed dose and annealing temperature on the micro-crosslinking structure and rheological behavior of three types of LLDPE with different branch chain lengths (Grades: 2045G, 2645G and 7042) were investigated. The results showed that the storage modulus and complex viscosity of the three types of LLDPE increased with the increase of absorbed dose, yet the damping factor decreased. The rheological properties of LLDPE were unaffected by the annealing temperature. When the absorbed dose was 5 kGy, the storage modulus of 7042, 2645G and 2045G increased by 815%、580% and 388%, respectively, indicating that the shorter the branch chain length of LLDPE, the higher the degree of micro-crosslinking. These results demonstrated that the three types of LLDPE with low absorbed dose formed micro-crosslinking structures, effectively improving their rheological properties and melt strength, highlighting the potential for modifying polyolefin products through micro-crosslinking structure of low dose irradiation.