In this communication, we prove some limits of the principal eigenvalue for nonlocal operator of Neumann type with respect to the parameters, which are significant in the understanding of dynamics of biological populations. We obtain a complete picture about limits of the principal eigenvalue in term of the large and small dispersal rate and dispersal range classified by "Ecological Stable Strategy" of persistence. This solves some open problems remainning in the series of work [3,32,30], in which we have to overcome the new difficulties comparing to [3,32,30] since principal eigenvalue of a nonlocal Neumann operator is not monotone with respect to the domain. The maximum principle for this type of operator is also achieved in this paper. K E Y W O R D S generalized principal eigenvalue, maximum principle, nonlocal Neumann operator, principal eigenvalue M S C ( 2 0 2 0 ) 35B50, 35J60, 47G20