The “dilution effect” of population growth is embedded into a four-sector level, buliding an growth model with endogenous microeconomic behavior, R＆D innovation and human capital accumulation, derived the BGP equilibrium and the factor influencing economic growth, in which a micro-foundation is analyzed to explain “The Battle of Signs”．The marginal contribution: there is a non-scale effect in the knowledge accumulation and“dilution effect”in the human capital accumulation, relaxed the prior setting about the upper limit or positive and negative with parameters. It suggest that the negative “dilution effect”and positive “thought effect”are microscopic transmission paths, the combined effect and different threshold value determines heterogeneity of economic growth influenced by population growth. Furthermore, the correlation between dilution effect and threshold value is analyzed，and the parametric effect is quantified by numerical simulation．
