Long-chain wireless sensor networks（WSNs） used in transmission line online monitoring presents some problems such as many hop counts and large delay.To optimize delay performance of WSNs

heterogeneous nodes that can communicate through wireless public network are brought in.Considering the uneven distribution of data caused by uneven deployment of sensor nodes

and effect on delay build the maximum delay model of heterogeneous WSNs; then considering that the network segments partition and effect of heterogeneous nodes deployment on delay

network optimization deployment method based on local search idea is proposed to optimize network delay.Simulation results indicate that the proposed method can effectively decrease the maximum network delay and improve the real-time of WSNs.