In the early stage of LTE deployment, LTE network coverage is limited, as a result, the network often switches. In order to ensure the continuity of the call, SRVCC is introduced, and SRVCC switching configuration uses A2+B2 event to be triggered. The research shows that although SRVCC has small difference in business performance with different thresholds, the switching success rate is worse when B2 RSRP1 threshold is reduced. By comparative analysis, this paper provides the reference for SRVCC parameter setting of VOLTE in different environments in the future.