This paper surveys ecological modelling and analysis from the viewpoint of large-scale systems. It will be very helpful to system scientists and engineers newly attacking these fields. It is time for a shift in emphasis from the numerical simulation of ecosystems to the theoretical discussion of fundamental principles. Several topics are presented, as follows: in § 2, the approximation problem—aggregation and decomposition; in § 3, ecological networks—input-output analysis, environ analysis, the information theoretical method, and the Markov chain method; in § 4, a macroscopic discussion—thermodynamical and statistical method, thermodynamic network analysis, and global models of energy flow and material cycling; in § 5, model identification—GMDH, compartmental systems analysis, reconstructibility analysis, and the flow-based modelling method.