In this artical, the construction of farmland-domestic animal ecological system in JiLin province An Tu county was analysed on the basis of the theory of system engineering.The best model of the general constructional readjustment about the fieid crops、domestic animals and medicinal plants in the system during the seventh five yearplan was devised with linear progreming method.The model embodyed the distribution and retional utilization of the agroclimate、soil and plant resources and included the function of the ecological balance among the climate, soil, plants, animals and population.The model provited a general means to chang the system from worse circulate to fine:expanding the paddy、soyabean and midicinal plants;reducing the like-warm crops, developing animal husbandry and readjusting the ecological regions of agricultur.The economical effect of the system would increase about 15.0 persent, and both the ecological and social effect will be very satisfactory.