In this talk, we discuss stage-structured predator-prey modeling from types of constant delay to that of state-dependent delay (hereafter SDTD). For the SDTD case, we consider the model with general nonlinear type of function response. First, for a large class of commonly used types of functional responses, including Holling types I, II and III, Beddington -DeAngelis-type (hereafter BD-type), etc, it is shown that the predator coexists with prey permanently iff the predator's net reproduction number is larger than one unit. Secondly, the local stability of equilibria of the model are also discussed. Finally, for the special case of BD-type functional response, it is shown that if the system is permanent, that the derivative of SDTD on the state is small enough and that the predator interference is large enough, then the coexistence equilibrium is globally asymptotically stable.