In this paper, a predator-prey system in a ratio-based predator with state-structure for predator is investigated. By using methods of the comparison principle and analysis, some sufficient conditions are obtained if -τ≤θ〈0, x(θ),y(θ)≥0,x(0),y(0)〉0, and then the solution of the system is positive for t≥0;If αre-rτ〉av, and then any positive solutions of system is bound-ed; and if r〉b/m and αe-rτr-m/b/a〉v, then system is persistent. Finally, numerical simul...