Because the scale of power cyber-physical system(CPS)is growing

and the existing cascade failure model ignores the information flow and the power flow transfer characteristics

it is difficult to quickly and effectively assess the survivability. Aiming at this problem

this paper proposes a quantitative survivability assessment method of power CPS considering load optimized redistribution. Firstly

according to the system topology and association

the degree-media weighted correlation matrix of power CPS is established by defining the degree function and the electrical interface

and the formal representation of coupled CPS is realized. Then

based on the structural connectivity change and risk propagation range of CPS cascade failure

the survivability assessment model is designed based on the constraints such as node load capacity limitation

optimal allocation strategy of information flow

power flow optimization equation and system safety operation. Finally

the chaotic Lévy search firefly algorithm is proposed to efficiently solve the assessment model. The case study shows that the assessment method can effectively quantify the survivability of power CPS and improve the assessment efficiency of large-scale coupled systems.