Nowadays, game theory is one of the most important fields in mathematics and optimization problems. Some important cases that could be pointed in the scope of game theory are internal and external policies of government in face of nation and other societies, technological development strategy, economic, relationships, war and power toward benefits improvement. The simplest state of game theory is occurred when all players are aware about the other’s goals and resource amount. One of the famous examples in game theory is Stackelberg’s games that first time begins in economy. A simple Stackelberg’s game is a two-player game called bi-level problem that the former player will receive a response from the latter player for determination of itself controlled variable. Feasible space and objective function for the both players are fixed and visible. A considerable question is that how much amount of controlled variable should be determined by the former player in order to obtain the maximum benefit? A tri-level problem is a bi-level problem that second level is a bi-level problem. It is proofed that a complexity of bi-level problem is NP-hard and inducible space of a bi-level problem is not necessary convex but it’s continues and set of extreme points of inducible space is subset of set of extreme points of feasible space. However, there is a difficulty for solving the tri-level problem, so that set of extreme points in inducible space are not necessarily a subset of set of extreme points of feasible space and inducible space at a tri-level problem against inducible space of bi-level problem is not necessary continues and there are not necessary way in inducible space of every extreme points of inducible space to at least one of extreme points of feasible space. This state is occurred when for a fixed and determined amount of first level’s variable the follower bi-level problem has an optimal multiple solutions. In this dissertation, the stated subject has been investigated to extract the multiple solutions of follower bi-level problem. The outcome of this survey is a method that generates these multiple points. Also, this method is illustrated by two examples.