OICC Press International Journal of Mathematical Modelling & Computations 2228-6233 7 4 2017 11 01 The Tau-Collocation Method for Solving Nonlinear Integro-Differential Equations and Application of a Population Model 265 276 EN Atefeh Armand Dep. Math, Yadegar imam khomeini (rah) shahre Rey, IAU Zienab Gouyandeh Dep. Math, Najaf Abad, IAU Journal Article 2017 11 01 This paper presents a computational technique that called Tau-collocation method for the developed solution of non-linear integro-differential equations which involves a population model. To do this, the nonlinear integro-differential equations are transformed into a system of linear algebraic equations in matrix form without interpolation of non-poly-nomial terms of equations. Then, using collocation points, we solve this system and obtain the unknown coefficients. To illustrate the ability and reliability of the method some nonlinear integro-differential equations and population models are presented. The results reveal that the method is very effective and simple.